I've fixed things so that bowling, vegas slots, and alien raiders display properly, and therefore can be played.
This site shows how some games should look like: http://home.comcast.net/~eichler2/microvision/MicroBowlSim.htm
(and you can play the games in your browser).
I'm a bit confused about alien raiders, i can see to press C to start, and E fires what i guess is a laser, but the laser doesn't destroy the aliens, and the game ends when one of them reaches the left hand side. Is that correct?