Resident Evil 4: The Mercenaries Mini-Game
Stone Librande

Trapped in a Castle

I’m cornered on the upper floor of an ancient castle and I can hear the enemy troops searching for me below. I don’t move. I try not to breathe. My heart is pounding so loudly that I’m afraid it will betray my location. I remain perfectly still while I wait for the rescue helicopter to touch down on the roof and save me from this nightmare. A long minute passes. Finally, I hear the helicopter’s rhythmic blades overhead. I’m exhausted, but euphoric. I feel like I’ve crossed the finish line after sprinting a mile, but I have not even moved a muscle. Now, confident that my mission has been successfully completed, I relax, let out a deep sigh…and drop my Gamecube controller to the ground.

Abruptly, I’m back in my living room standing 3 feet away from the television screen. I had been so deeply immersed in my game of Resident Evil 4 that my body was convinced it had been trapped in that castle. I can still hear my heart racing and feel the adrenaline flowing through my veins.

Then it occurs to me. I had just experienced one of the most immersive, suspenseful and physical videogame moments of my life and I had been doing absolutely nothing for a full minute. I didn’t pull a trigger, move a joystick or push a single button. I had been standing perfectly still staring at an empty stairwell on a television screen and watching a clock countdown from 1:00 to 0:00. How could doing nothing be
so exciting?

To answer that question, I decided to examine Resident Evil 4 more thoroughly. I had been playing The Mercenaries portion of the game, which is only a small subset of the full game, so I thought it would be easy to break down the game mechanics. I began by mapping out the reward moments and the gameplay arcs, but I soon realized that the answer could not be found by studying only that one game. To get the full picture I needed to factor in all the games of The Mercenaries that I had played that night (about 30 of them), as well as the previous two weeks of gaming sessions (probably more than 300 games in total).

The Mercenaries Mini-Game

Resident Evil 4 was originally released for Nintendo’s Gamecube console by Capcom in January 2005. It quickly became one of the most popular games for the console and won numerous awards, including Game Informer’s “2005 Game of the Year”. Subsequently, it has been released for the PC, PS2 and Wii consoles.

I had spent several long nights playing through RE4’s campaign story and I also rank it high on the list of my best game experiences. But as good as the campaign is, it is not at the top of my list. That honor belongs to The Mercenaries, a mini-game that is hidden on the RE4 disc. You cannot simply play Mercenaries from the main menu; you first must prove yourself worthy by beating the story mode.

The rules to Mercenaries are simple. You are placed on a small map and have two goals: survive and score points. If you die you lose all your points and the game is over. If you survive you are awarded “stars” based on your score. Score 60,000 or more points and you get 5 stars, which is the highest rank.

All this seems like standard videogame fare: kill mutants, get points, don’t die. So what is it about Mercenaries that puts it at the top of my list? Rather than gush about my emotional responses to the game (which were both numerous and powerful) I want to take a more logical approach and deconstruct the game into a series of timed reward moments. By mapping out these rewards, and the intervals between them, we will see that Mercenaries is constantly rewarding the player. And as long as there is a meaningful reward right around the corner then the player is in a situation where he or she feels compelled to continue playing. Mercenaries not only achieves this on a second-to-second and minute-to-minute schedule (many games get that right), but it also succeeds on daily, weekly and monthly schedules.

100 Stars

A fundamental way of understanding any game’s structure is to break it down into a series of rewards that pull the player through the experience. If the rewards are too far apart then the player may lose interest before completing the game. Conversely, rewards that are too frequent often stop feeling like rewards; the constant repetition causes them to lose meaning. A central goal of any game designer is to find the balance between these two extremes. To see how the RE4 designers achieved this goal we will start by looking at the most infrequent rewards and then working our way down to the most frequent rewards.

At the highest level, The Mercenaries mini-game is itself a reward. It is a bonus game that can only be unlocked when you beat the main RE4 campaign game. So right from the start you already feel special; your skills at RE4 have earned you the privilege and honor to play Mercenaries. Of course you feel compelled to try it at least once.

But after the first few attempts what compels you to keep playing? The carrot that is dangled in front of you is the ultimate unlock: the Hand Cannon! This magnum pistol is by far the most powerful weapon in the game. (For comparison, a fully upgraded semi-automatic rifle is rated at 15.0 firepower, while the Hand Cannon is rated at 99.9 firepower). Replaying RE4’s campaign with this destructive weapon in your arsenal will essentially turn you into a god, as even the toughest bosses die in two or three shots.

Of course, a legendary weapon like the Hand Cannon is not going to be easy to obtain. To prove your worthiness you need to earn 100 “stars”. Stars are simply a measurement of your score and, more abstractly, your skill level.

There are 5 characters in Mercenaries and each character can earn up to 5 stars in each of the 4 different levels. You start the game with Leon, the hero featured in the main story. Leon is a jack-of-all-trades character who is good at everything but not particularly strong in any one category. Since you have to beat the campaign game before you can play Mercenaries then it is guaranteed that you will already be familiar with him and know what to expect.

Leon can play on four different levels and each one emphasizes different strategies. The Pueblo is an open farming village with one and two story buildings and barns. The enemy can come from any direction and you have to continually watch your back. The Castle is a medieval maze-like complex with multiple staircases and balconies. This level has several key choke points but you have to be careful or you will be cornered with nowhere to run. The Military Base is a combination of trenches and twisting caves in a mountainous desert environment. You tend to go toe-to-toe with enemies in the passageways as you move from one zone to the next. The fourth level, Towers (or Water World), features several multi-story open structures surrounded by water and connected to each other by a series of ladders and walkways. Long range attacks are favored if you can hold the high ground.

After achieving a 4-star rating on any of the four levels you unlock a new character. Each character has a set of unique talents and weaknesses which forces you to change your play style. Ada is unlocked on the Pueblo level. She is the fastest character and has ninja-like close range attacks. While playing her you are encouraged to keep moving. Krauser is unlocked on the Castle level. He is the toughest character and has a unique demonic arm that deals a devastating short range attack. HUNK is unlocked on the Military Base. This gas-masked soldier starts with a machine gun and is good at mowing down crowds of enemies from a distance. The final character, Wesker is unlocked by getting a 4-star rating on the Towers level. He is the best of all the characters at long range with his upgraded sniper rifle. At close range he pushes enemies away using a powerful psionic blast.

The combination of the 4 levels times the 5 characters creates 20 distinct challenges to master. Because the characters have their own special traits and weapons you will find that beating the Castle level with Leon is a different experience from beating it with Ada. The variety in the level design also means that the same character needs to use different strategies depending on his or her location. Playing Wesker in the Miltary Base requires different skills than playing him in the Towers.

So although the rules of the game remain the same across the challenges (stay alive and score as many points as possible before time runs out) each challenge has a unique feel, as if you were playing 20 different games. This keeps the gameplay fresh, which is important since you might be playing for a long time. It can take over 40 hours to master all the character/level combinations and accumulate the
100 stars.

Session Improvement

You can earn up to 5 stars per challenge, but it is unlikely you will be able to do this on your first attempt. In fact, on your first try you will probably die a gruesome death as you make a wrong turn and stumble into a crowd of axe-wielding mutants. In general, it will take an hour or two of practice before you memorize the level layout, the enemy positions and attacks, and how best to use your character’s unique skills to your strategic advantage.

One of the great features of Mercenaries is that you can literally measure the improvement in your skills as you gradually, and consistently, get better with each replay. What feels like an insurmountable obstacle in your first play through will become a simple (and routine) task as you refine your strategy. Although your score may vary up and down from one game to the next the overall average score will tend to rise over time (the straight black line on the graph below).

Another important factor that adds to the game’s replay value is that each game is relatively short. An average game takes only takes about 5 minutes to complete. This encourages a “one more try” attitude. No matter how long you have been playing it seems like you can always spare 5 more minutes to try again. When you beat your previous best score you will want “one more try” to see if you can continue the trend. When you die early due to a stupid mistake you want “one more try” to make amends. When it is past midnight and you need to get up early for work the next day then it is easy to rationalize “one more try” because you will only be losing 5 minutes of sleep.

The star system acts as a set of milestone markers to gauge your overall progress. Getting one star is trivial (as long as you stay alive) and you will achieve that milestone quickly. 2-star, 3-star and 4-star scores will happen within the first hour as you begin to find and exploit effective patterns. At this point the game fools you into believing that your 5-star score is right around the corner. After all, you are on a reward schedule that is handing out 1 star every 15 minutes of play. But in reality this is about the time that the game gets serious. You will likely need an hour or more to get that last star.

Notice that the difference between a 4 and 5-star game is 30,000 points. Essentially this means that a 5-star player needs to be twice as skilled as a 4-star player. Even with a linear progression in scoring it will take you twice as long to achieve your 5th star as it did to achieve your 4th.

It is not uncommon for a player to get frustrated around this point. After all, the first 4 stars were doled out at a fairly fast and consistent pace. Suddenly, the player feels like he has hit a wall and the rewards stop coming. In many games this would be the catalyst that makes a player quit for good. The designers seem to have anticipated this, because right when you reach a 4-star ranking a new character is unlocked for you to try. Instead of quitting in frustration you have a new option: try out your new toy and, at least temporarily, forget that you are stuck.

As you continue the game you begin to notice that you are improving. Over time your score has been growing. Slowly, but noticeably, you are inching up on the 60,000 mark. This feeling of constant progress, however slight, instills a sense of hope and increases the need to try again. As your skill continues to rise you will inevitably get a score in the high 50 thousands. These games prove to you that a 5-star game is possible. After each game you start to identify the one key event that kept you from getting that final star. Maybe you forgot to reload during a quiet period and ran out of ammo in the middle of a crowd. Perhaps you threw a grenade too early and took out only one mutant instead of the five you hoped to kill. In any case, it will be hard to avoid the urge to immediately hit the “Replay” button as you attempt to get it right the next time.

Perhaps the worst mistake you can make is to reach the 60,000 mark and then die before the helicopter rescues you. No matter how high your score, you do not get any stars if you are dead. That period of time between certain victory and utter defeat is without question the tensest moment in the game. You no longer need to score points; you only need to stay alive. Unfortunately, this is trickier than it seems since enemies are lurking around every corner. If you make one bad move all your effort will be lost.

If that unfortunate event occurs (and there is a high likelihood that it will at least once in your 20 challenges) then you will have to suppress your powerful negative emotions. (Like the urge to throw your controller through the television monitor.) Instead, take a deep breath and look at the bright side. You have just proved to yourself that you have the skills you need to break through the 60,000 point barrier! This brush with a 5-star game, though painfully frustrating, will not make you quit. Instead, it has the opposite effect. You immediately hit the replay button, certain that victory is inevitable.

Over the next 10-20 games everything comes together. You have memorized every nook and cranny of the level, learned the strengths and weaknesses of both the enemies and your hero, and perfected an optimal route that takes you to all the weapons, ammunition and health vials. You have discovered the choke points where you can take out a room full of mutants at once, and you avoid being cornered in the death traps where there is no way to run. A 5-star success is now only a game or two away.

Second-to-Second Moments

The meta-game of collecting all 100 stars, and the session game of beating a 5-star character/level challenge, are both excellent examples of how to enhance replayability and get a player hooked over long periods of time. But it would all be pointless if the core game were lacking in its own rewarding moments. An individual game of Mercenaries is a tense and exciting experience from beginning to end. The reward moments range from second-to-second decisions (attack or flee, shoot or reload, explore or hide) up to the final game goal (stay alive until time runs out).


The strongest pressure on the player is the game clock, which initially starts at 2 minutes. The clock is prominently displayed in the upper left corner of the screen. It shows the remaining minutes, seconds and hundredths of second. The bright white numbers make it hard to ignore. (And when there are only 30 seconds left it turns blood red and flashes, guaranteeing that it will not go unnoticed.) In fact, the timer appears larger than your score total, which sits humbly below it. The timer is a constant reminder that every second is precious and, like a bass drum rock beat, it sets a fast, powerful tempo for the game.

Unlike a typical race game that requires the player to complete a certain task before a timer runs out, Mercenaries uses the countdown to determine victory, not defeat. You win the game when time reaches 0:00. Your goal is to avoid dying before
that happens.

Unfortunately, you cannot achieve a 5-star rating with the initial 2 minutes of time, so you are forced to find the glowing orange time extension bonuses that are scattered throughout the level. Each one you touch adds either 30, 60, or 90 seconds to your clock. Whether or not to increase the timer is a risk/reward decision. By extending your time you are potentially maximizing your score but you are also giving yourself more opportunities to die (and losing all your points) before the timer runs out.


Riding on top of the persistent clock beat is the combo system. The basic combo rule is simple: you score progressively more points for each successive kill, as long as each kill is made within 5 seconds of the last. Like the clock, the combo counter is not subtle. It appears in large white letters in the upper right corner of the screen and cannot be ignored. It blinks aggressively when the combo is about to expire, taunting the player to kill something…soon! If the timer is the bass drum then a combo is the guitar riff. Each combo is a freeform period of energy that gets more exciting the longer it continues.

The gameplay effect is that the player feels forced to fight. This is not a game about hiding, waiting and biding your time. You need to constantly keep in motion and actively seek out things to kill. The more mutants you find in a group the better your chances are at keeping the combo going. Once again a strong risk/reward pressure is revealed. More enemies equal more points, but heading into a mob of mutants significantly increases the chance that you will die and lose everything.


Another way to increase your score is to pick up the bonus point power-ups that appear in each level. Once activated you have 30 seconds to score bonus points with each kill. This provides yet another risk/reward decision since the best strategy for using these is to make sure a lot of enemies are nearby before activating the bonus. Trigger a bonus power-up too soon and it will be wasted. Trigger it too late and you will dead.


When the level begins you will see only standard enemies. But as time goes on you run the risk of bumping into boss enemies. Each level has its own unique boss (chainsaw-wielding peasants, a man-beast with giant claws strapped to his hands, a mutant soldier with a rapid-fire machine gun, and a dual-chainsaw wielding monstrosity called Dr. Salvador Sr.) which requires a different strategy to defeat. Of course, these baddies are tough to kill but can usually kill you with one attack. No matter how healthy you are it is hard to survive a chainsaw to the head. It is possible to avoid the bosses by running away when they are near, but then you will miss out on a huge point bonus (almost 25x as much as a common enemy). Killing a boss (or two) is the best way to get a high score. Unfortunately, fighting a boss is also the most common way to die.

Another interesting risk/reward tradeoff is that the chance for a boss to spawn increases the longer you are on the level. So if you add extra time on the clock (which you will, if you want a high score) then bosses will start to spawn quicker. If you manage to collect all the time extension bonuses then it is likely that you will be attacked by two bosses at once by the time the game is nearing its conclusion.

Weapons, Ammo and Health

Interspersed at approximately 15 second intervals are the standard set of decisions that appear in most videogames with weapons:

Which weapon should I use now? As the game progresses the enemy groupings change and you need to quickly switch to the best weapon for the job at hand. When the enemies are far away and unaware of your presence then it is a good time to equip the accurate, but slow-loading sniper rifle. If the enemies are grouped together in a tight room then lob a messy, devastating grenade. If you are running low on ammo then you might want to consider putting away your gun and slashing with your trusty knife.
Is it safe to reload? Should I use all my ammo now or save some for later? Should I pick up that ammo on the ground now or wait until all the enemies are dead?
Do I have enough health left to survive this battle or do I need to run away and eat some colored herbs (RE4’s healing potions)?
Finally, it is worth noting that in addition to points, each kill has the potential to drop a box of bonus ammo or an extra vial of healing herbs. The message is clear: You need to kill if you want keep on killing. You need to kill if you want to stay alive. You need to kill if you want a high score.

Back in the Castle

It should now be easier to understand my frame of mind on the night that I was trapped in the castle. It was past midnight on a weekday and I had been playing for over two hours straight. Because I play video games standing up just a few feet back from my television screen (a habit I picked up by spending my teenage years in video arcades) my legs were sore and my eyes were dry and stinging. I had to get up early and work the next day but I continued to tell myself, “This one is the last one—no matter what—and then I’m done for the night”. I must have repeated this mantra, to no avail, after each of the last 20 games.

When I finally broke the 60,000 barrier I had over one minute left on the clock before the helicopter arrived to rescue me. Previous experience had taught me that running around was a sure way to die. So this time I decided to back into a corner on the top floor and wait for the enemy to come to me. They never did. Anticlimactically, nothing happened. I ended up standing there, my gun pointed at an empty stairwell, waiting. Yet, I was completely engaged, to the point where there was no TV, no controller and no living room. All that existed for me for that minute was a stairwell, a gun and a clock.

I was completely hooked. At that instant I knew that I would have to collect all 100 stars and unlock the Hand Cannon. Over the next week I continued to stay up late and play Mercenaries. As my experience with the characters and my knowledge of the enemies grew I noticed that I was completing the levels faster. What used to take over two hours was now taking less than one. The end was in sight, which only increased my desire to play more.

Strangely, when I finally beat the last level with the last character I did not feel excited. In fact, I felt a bit sad. It was the same feeling that you get when you finish the last page of great book. You do not want it to be over. “Well, at least I unlocked the Hand Cannon”, I thought.

The next night I loaded up the campaign game, ready to start all over again with my Hand Cannon. I equipped my powerful weapon, shot a couple of mutants, and quickly noticed that my motivation was gone. I had reached the end of the reward chain and had no reason to continue playing. I exited the game. After more than a month immersed in the world of Resident Evil 4 I knew it was time to move on to another game and face new challenges. My Hand Cannon had gone from being the ultimate weapon to being little more than a trophy, another dusty memento on the virtual shelf that holds my collection of video game memories.