SWAR!

SWAR is a two-player space combat game, based on the ancient early video game Spacewar. You are placed in a bordered-space environment and must blast the other player and/or help them run into the sun in the center, which has a gravity-like effect. Pressing F1 will show in-game help and F2 will allow you to adjust multiple options which could make the game more fun or add some variety, including choosing different ships with slightly different properties. Overall it's a pretty simple game but if you have two players sharing a keyboard it could be fun!