Atomic Blast is an action platformer that features twelve short levels, created by qrleon using an unregistered version of Game Maker. Similar to Chris Roper's Destructivator, you play a hero who can jump, climb, and shoot his way past just about every obstacle thrown at him. Our protagonist isn't exactly invincible though, as getting hit by a single bullet from any enemy's gun will kill him instantly.

Be prepared to face a boss at the end of the twelfth stage as well, although there isn't any special strategy required to beat him (other than shooting at him repeatedly and avoiding all of his attacks). You can grab the game directly from here, then use the free 7-Zip software to unzip files with 7z extensions. (source: dessgeega)

Stages 1 - 11

Final Stage