The help doesn't display right also, disabling the delay before key repeat would be nice. Also, transparent background for sprites please apart from that, looks like a good start

I like it. Very simple concept but a lot of fun.

3 things: I have to exit the whole game after losing in order to play again. Maybe be able to restart?  Also if the other players would shoot at directional angles (at the player and other players) that would be awesome. Is there a way to win? I keep losing, but it looks like the other people either aren't affected by paintballs or just respawn after a bit.

Keep up the good work!

A little trick to movement that could help, if you know enough about timers you can get the amount of time the last tick took in seconds and multiply that be a speed value to get x pixels per second. That's how I do animation in all my games, at least.

You can also make a color transparent in VB.Net using the Bitmap.MakeTransparent() method. It'll take a color as an argument, and in that bitmap it'll make any pixel with that color transparent. So in the case of your sprites, that would be white.

http://msdn.microsoft.com/en-us/library/8517ckds(v=vs.110).aspx?cs-save-lang=1&cs-lang=vb#code-snippet-1

For AI firing, you might want to consider having the AI fire at the player, but generate a random offset for the angle of firing so that there's an unpredictable error to it. So far the game is too easy.