Copy Killer

As one of many clones, you are trying to escape. As a team effort, you must kill others and then die so that a sole survivor can continue in the quest to escape. You then take over control of the survivor to continue in the quest to save the institution of clones.

Spoiler: The objective is to find the messages (small piece of paper). These appear randomly in levels, so even if you go to every level you might not get them all. Just go back and they will appear. There is a random chance every time you start a level that a message will be available. You will normally have to visit levels more than once to find all of the messages.
To open the doors, you need to kill all other clones in the level, then kill yourself. If you read the messages it explains why, but basically the doors open when there's only one clone left, it can't be the one you're controlling. Once the doors open, you need to get the remaining clone out the door, so before you die be sure to set it up so that this will happen. Once the clone gets out the door, he arrives in the room next door to the right or left (depending on whether you left from the right or left of the room). You then take control of this clone. Rinse and repeat.

Controls: Arrow keys to move, Up to jump, Space to pick up, drop or throw, and Enter to continue on various screens.

System requirements: This game requires a recent HTML5 compliant browser. A browser supporting WebGL is suggested, but the game will run (albeit slower) without.

Source: This game was made with GameMaker HTML5 and was entered in the Ludum Dare #22 competition. You can download the Windows EXE version (includes GameMaker project file [source]) here.