Xong is an odd and idiosyncratic munge of a Rogue-like, a level-based puzzle game, and an Arkanoid clone. It's Rogue-like, in that it's an ASCII graphics game with procedurally-generated levels, but the actual gameplay is puzzle solving with Breakout-like aspects.
You're a white square that moves with the arrow keys; scattered about the level are a bunch of colored bricks along with some enemies, and a level exit. The level exit is colored, and to use it, your "puck" must be of the same color. It's also generally located someplace hard to get to initially.
You can eliminate bricks by shooting your puck at them (CTRL plus direction); the puck picks up the color of the last brick it eliminated (but is white by default). You can, if you want, let a puck bounce around, Arkanoid style to eliminate a bunch of bricks, but it only moves in cardinal directions. There are usually some spare pucks lying around to pick up, which will be necessary if you lose your puck in a black hole.
The only way to eliminate enemies is to direct them into a black hole with "chevrons" -- direction indicators that you lay with ALT + direction key. Chevrons also affect puck direction. Enemies move in predictable, Pong-like ways, so they're fairly easy to avoid, but leave a red line behind them, Snake-style, which kills you if you intersect it, though it gradually disappears behind them.
It's actually pretty interesting, although in common with other Rogue-likes, you can get dull levels, and can also get into a condition whereby the current level cannot be solved. There's no level restart or save game, so you don't have a recourse other than starting over. It's pretty imaginative, though.