Uo Poko

Mention CAVE and most people picture screens saturated with bullets. Uo Poko, from 1998, is therefore an odd entry in the company's catalogue: an arcade puzzle game where nothing gets shot down, only bounced.

The principle reads instantly. You fire a ball upward into a cluster hanging above, matching three or more of the same colour to clear them. The whole mass creeps downward as you play, and the game ends when it reaches your level. Tension is built into the movement of the screen itself — every misjudged shot adds a ball and pulls the ceiling closer.

As a design this genre is unusually well balanced. The rules take ten seconds to understand, but mastery lives in chain planning: a well-placed shot can drop a large section of the cluster at once and buy you half a minute of breathing room. On top of that sits the bank shot, using wall angles to reach positions a direct line cannot touch, which is where experienced players separate themselves from beginners.

Running on hardware designed primarily for shooters meant the presentation could afford to be colourful, clean and finely animated. That is not decoration in a puzzle game — colours have to be distinguishable at a glance, without the half-second of doubt that costs you a shot.

On OldGame.cz it runs directly in the browser. This is the kind of game that works exactly as well now as it did in 1998, needing no context and no explanation, and five minutes turns into half an hour with alarming ease.