Game Design Analysis: rRootage

I’m going to start analyzing games, to find the parts of their design which make them fun. By doing this, I’ll start to understand how a well-picked set of mechanics come together to make a fun game, so that I’ll have a better shot at making fun games myself =).

The two components of a game’s design I’m going to look at are the core and the mechanics. The core is the game’s central theme, it defines the type of experience the game will deliver. The mechanics are individual features or activities in the game which support it’s core.

I’ll treat the mechanics as areas of learning: every mechanic provides a learning opportunity to the player. The better the player gets at exercising each mechanic, the better they play the game. The challenge is to provide an optimal learning curve, where the mechanics are intuitive and easy to pick up, but aren’t immediately mastered. As long as the player is improving, they can enjoy a continually changing experience.


I’m going to start off by analyzing a great indie shooter, rRootage, by Kenta Cho of ABA Games. It can be downloaded for Windows from its web site, and Linux and Mac OS X ports are available. Use the directional keys to move, Z to shoot, and X to use your alternate ability, which depends on the mode you play.

The main screen, with many levels to choose from.

The title screen, with lots of levels!


The core of a game is, put simply, what the game is about. rRootage is a 2D shooter where you maneuver through complex volleys of bullets in order to defeat boss enemies.


Player movement in rRootage, despite having a very simple interface (just the directional keys), is actually very deep. Although the mechanism for controlling your movement is easy to understand, learning to make effective use of these controls in dangerous situations is hard.

Because the movement controls are digital, you only have one movement speed. In practice, you often need to move a very small distance, or move at a slower speed than the default. For example, you might have to navigate through a small opening in a volley of bullets. To properly navigate through, you need precise control over your motion. The way to succeed is to learn to move in small bursts, by just tapping the movement keys with good timing.

Another thing to keep track of is your overall position on the screen. In order to win, you have to destroy the enemy by firing at it. Since you can only shoot straight forward, you have to position yourself directly in front of it to hit it. You also do more damage the closer you are to the enemy, which puts you in a more vulnerable position. What’s interesting is that this issue varies in importance as you play, since when you are in danger of being hit you tend to focus on survival, whereas when you are safe you can make an effort to move back to forward centre. This automatic adjustment means you’re never bored while playing, because you can vary the difficulty of play based on where you move.

Daringly closing in on the enemy increases your damage.

Daringly closing in on the enemy increases your damage.

Recognizing Repetition and Patterns

The first few levels are pretty simple, as the enemies don’t fire too many bullets at you. As you get farther, though, they fire more and more, until you have entire clouds of bullets flying toward you. They aren’t just fired randomly, they have an order to them. You can’t keep track of each bullet coming at you, so you have to look for patterns in order to figure out how to avoid them. On the other hand, when bullets come close to your ship, each individual one could mean death, so you have to keep track of them individually.

If you devote your attention to the blue bullets, the incoming ones might box you in.

If you devote your attention to the blue bullets, the incoming ones might box you in.

As a result, you’re always torn between two opposites: keeping track of the bullets which are right around you, so you can maneuver around them, and keeping track new volleys being sent at you, to predict where they will go and how to avoid them. The first keeps you alive in the short term, but unless you plan ahead you end up being swamped with nowhere to go.

Mode-specific Mechanics

rRootage has four modes of play. In addition to the basic mechanics of movement and pattern recognition, each mode adds a mechanic of its own.

NORMAL mode gives you three ‘bombs’ to use. Setting off a bomb puts up a temporary shield around you which absorbs enemy bullets, and every time you die your bombs are replentished. Each bomb gives you one opportunity to avoid death, if used at the right time. Finding the right time is hard, though: if you use them too often, they’ll run out, leaving you defenceless, but if you’re too sparing you end up dying with bombs left over, which is also a waste.

This would be a good time to fire a bomb.

This would be a good time to fire a bomb.

PSY mode lets you ‘graze’ enemy bullets: if you move very close to one you get a small amount of charge from it. Fill up your charge meter to become invulnerable for a short time. Using your special ability, you can trade some movement speed in order to increase your graze radius. Lowering your movement speed can even be useful to tighten your controls. This mode encourages you to take risks and put yourself in dangerous situations, because you can use the temporary invulnerability to fly through a solid cloud of bullets you wouldn’t normally be able to navigate.

IKA mode is inspired by the excellent shooter Ikaruga. Enemy bullets are coloured either white or red, and your ship has a shield which you can alternate between the two colours. If you come near a bullet with the same colour as your shield, it’s absorbed and deals a little damage to the enemy. As you’re permanently protected from half the enemy bullets at any time, this mode throws much denser volleys at you. This means that to survive you need to keep switching back and forth between the colours. This is a challenge, because every time you change colours you have to mentally switch, to avoid the other colour. The sudden foreground-background switch is something you get used to to some extent, but it makes this mode feel much more urgent than the others, since it requires more quick thought.

Finally, there’s GW mode. GW mode is similar to NORMAL mode, except that you have an infinite number of bombs. The catch is that each bomb takes about a second of warmup before it fires, and there’s a several second cooldown afterwards before you can fire it again. On the upside, these bombs absorb bullets and damage the enemy in the same way IKA mode’s shield does. You can obviously be much more generous in your bomb use than in NORMAL mode, but because of the warmup delay they can’t be used as safely for escaping emergency situations. Instead, you have to think ahead and plan when to use them.


rRootage is a pretty simple game, but the variety of different levels and modes makes it last a good long time. Because of that, it’s been one of my favourite shooters for a few years now. Go check it out, and if you enjoy it (or think I missed something important), please leave a comment!

Posted on 2009-02-01 at 10:25. trackback