It's not often you find a bundle of entertainment this small. Here's a featurerich game that boasts a dussin plus levels, almost the same amount of enemies, a small array of standard weapons and a great soundtrack. There are no spectacular intro screens, no save points, no nonense. It's a fastpaced runthrough action drama (it has a storyline, though) that at least I enjoyed playing. Download the game at the bottom of this post, and here's a link to the official website. The game is free to download, upload, and share, so feel free to play it as well. There is no readme or ingame info included, so here's a quick guide (probably the only one, too) for the game (might build upon it later, so keep the link if it is of interest).
FIRE - Left mouse button
OPEN/SELECT - Right mouse button
INVENTORY/SKIP - Space
TOGGLE VIEW - Enter
MOVEMENT - Arrow keys
Your standard weapon never runs out of ammo. All others use the same ammunition cartridges. There are plenty to fill up your weapon with, but be sure you have enough to spare.
Pistol - Standard weapon.
Rifle - Faster and more powerful than your standard firepower.
Shotgun - Lethal on close range, can hit multiple enemies from further away.
Machine Gun - Doesn't do as much damage as the rifle, but fire much much faster, and it eats your ammo, too.
Shoot anything that moves, open anything that looks like a door, and press the button at the end of each level to move on. There are over a dussin levels in total, and a few "boss battles" inbetween. There isn't much strategy involved, just be sure to stay away from enemy bullets, and yet get close enough for your shots to do any harm. There is health and ammo to collect on a regular basis, but no save points, and you only get three chances to continue, so don't die too much. Have fun!