25

25 is a platformer with 5 single-screen levels. The goal of each level is to collect all diamonds, avoid the obstacles (mostly stationary enemies which periodically shoot projectiles and a few moving dangers) and reach the exit. Each contact with an obstacle means instant death and respawns the protagonist at the starting point of the current level, but after the fifth death the game is over.

The main gimmick is the inability to jump. In order to reach lower platforms, the player needs to drop down from higher ground. The falling speed is relatively slow which allows to move left or right while in the air. This is necessary to reach some diamonds and because there are no ways to climb back up, the only way to collect a missed diamond is to die.