Catrap

A prototypical puzzle game, as in a game that makes it abundantly clear how the barest mechanics should interact in order to produce interesting levels. Owing to its origins as a BASIC type-in game,¹ the mechanics are extremely simple: moving into a block will shift it forward one tile, moving into sand will make it disappear permanently, preventing you from walking on it later, and moving into an enemy will remove it, with the win condition being removing every enemy. Every object shares key attributes: everything in the game can be walked on by the player character and almost everything has gravity apply to it (excluding sand, ladders, and some enemies). There is no concept of death, no dynamic objects, and no theme-driven levels that add or subtract mechanics. The only twist here – which is seemingly unique to this Game Boy release – is that specific levels have you control two characters at once, with the select button switching between them. The clarity and versatility of this mechanic primarily derives from it following the aforementioned rules: you can walk on the idle character, and gravity applies to them at all times, just as if they were another block in the world.

Compared to its block-pushing cousins under the Sokoban umbrella, the gravity helps clarify the state space, as most of the vertical positions collapse into a single falling sub-action rather than having individual idle positions in-between. Regardless, it still adds causal layer to every action, as dropping an object will affix it to its new vertical position, with no way to raise it after the fact (assuming it’s not your other character). As mentioned in my Polarium Advance review, symmetric puzzles succeed when solving one side makes the solution for the other side drastically different; Catrap accomplishes this by forcing the player to drop objects down to accomplish preliminary objectives. Since enemies can hold objects above them or be used as a walkway, removing one to draw closer to the goal changes the player’s access to other parts of the level. Through this lens, the sand blocks accomplish the same goal without the restraint of gravity, and their irrelevance to the objective gives the designers opportunities to confuse the player by laying “red herring” sand blocks throughout the stage, making it unclear which actually matters for the level solution.

In Round 44, one can make out the primary goals from the structure: the player needs to push a block over to the right side to access the enemy on the ladder, and they need to leave themselves free afterwards to access the top left to end the level, as removing those two enemies will unavoidably trap the player. Untangling the mess in the middle revolves around those two tasks. In Round 99, a similarly structured level, the amount of possible states and removable/moveable objects in the giant heap on the right makes much of the initial exploration blind, rooting about for how the seemingly random arrangement of blocks will evolve and where the pain points will arise. Admirable, but also tedious.

I use the language of the state space model here because it applies so beautifully to this game, to the extent that the game acknowledges it through rewind/replay buttons that move the player one state forward or back in time without restriction. It’s an essential mechanic; the downside of this system is that, as the game wears on, the player must exhaustively plumb the larger and larger state spaces for the one true solution, a task that would put off any sane player without extremely generous rewind. The designers evidently felt comfortable with their system, orchestrating large stacks of objects intertwined in the late game that must be picked apart in specific orders to avoid locking away enemies or stranding the player. It would be even more unpleasant if the game didn’t have a laissez faire approach to progression. 99 of the game’s puzzles are available from the start, with only one final puzzle remaining once all of these are finished. Jumping around and playing the good content in a modular format lets the player hone in on the quality. Those moments are when the game can reveal its hand just enough to let the player know what the core goals are in a level while leaving some part messy enough to require trial-and-error. One may have more fun tackling the rest by programming a solver.