Digging games and shooting games go together like eggs and peanut butter. I'll let you sit and ponder that one for a while, then feel free to come back and play the harmonious selection of games below!
Excavatorrr (Windows, 1.2MB, free) - One can never have too many digging games. Excavatorrr by Hempuli and Noby is a visually simple game where your goal is to find treasure by digging underground. Carry a few items with you as you maneuver through the passageways, such as bombs, ladder kits, and dynamite, to help you deal with the various obstacles packed in the dirt. You'll also have to contend with enemies, although it's usually better to avoid them whenever you can. Make it to the bottom, nab the golden idol, and truck it back to the surface to win.
GunFu Deadlands (Windows, 6.7MB, free) - Think you've got what it takes to survive the wild west? Well, unless you have a time machine, you'll never know, will you?! You can, however, see if you've got what it takes to survive in a wild west-themed arcade game by Christiaan Janssen. Move with the [WASD] keys, fire with the mouse, and use bullet time to slow things down for a few seconds. Take out all of the baddies to move on to the next level. You can't go charging into gunfights in this game, as one shot sends you packing. Take it slow, watch the enemies move, and make good use of bullet time and your jumping ability.
Angry Gorilla Machine Monsters (Windows, 2.7MB, free) - A simple shooter by Andrew Brophy with a presentation many games wish they could emulate. Move with the [arrow] keys, fire with [Z], and see how long you can stay alive. Enemies are random, so every time you play you could see something new. The gameplay is really basic, with no power-ups or other bonuses to keep you interested in playing. You'll get several great runs out of the game, though, and the audio/visual package really is something you should check out.
Note: All games have been confirmed to run under Windows Vista and are virus-free. Mac users should try Boot Camp, Parallels, or CrossOver Games to play Windows titles, Linux users can use Wine. If you know of a great game we should feature, use the Submit link above to send it in!