Serious question: if you were a failed experiment of genetic engineering, what would be your weakness? In the case of the poor critter from this week's game Abandoned, it's a limited supply of oxygen. Personally, I would be unable to comb my hair without first dislocating my left shoulder. Think about it. That'd be a rough life.
Caster (Mac/Windows, ~20MB, demo) - A 3D action adventure game that brings back a lot of memories from the Nintendo 64/PlayStation era. Dash, jump, fire, super jump and walk your way through a series of missions as you destroy bug-like creatures and collect energy orbs they leave behind. After each level you can upgrade your abilities tower defense-style. You (and some enemies) can even deform the terrain, which is a nice (and epically dramatic) touch.
Abandoned (Windows, 12MB, free) - A simple game of exploration that brings back fond memories of Super Metroid. You play a creature who is the result of a failed genetic experiment trying to escape the lab. You have a limited supply of air and must move quickly to find the right power-ups to clear the way to freedom.
greenTech (Windows, 15MB, free) - Eliminate global warming in this deliciously retro strategy game from the creator of Shellblast. Steer the wind by moving the hurricane (cursor) to pull clouds of pollution from factories into the cleaning facility. If only it were this easy (and fun) in real life!