I would highly recommend you try some of these games out for your computer.
Mega Man: Go through and defeat the end bosses in the various levels. Hint: Try to find the right suit to use as you face the different bosses.
Sonic: Race around as Sonic and collect coins. The levels are pretty fun to go through, which makes this an enjoyable game to play. Hint: Find as many bonus stages as you can.
Bubble Bobble: This is just a fun waste of time :p Put your enemies in bubbles and then go pop the bubbles. Simple, easy, and amusing.
Serious Sam: Ahh, yes, one of the greatest games ever made! It has everything one could possibly wish for in a shooter game: gore, violence, machine guns, explosives, suicide bombers, etc. Wreck utter havoc to the alien monsters! Hint: There is no hint. Just go kill things.