A series of platform Flash games created by Diseased Productions without a lot of the usual platformer tropes. You play as Experiment #154 fighting against the corporation who created him to control and use as a weapon. The hero uses a variety of high-powered guns and (in Thing Thing 4) a lead pipe.The line of games can be found here.
Artificial Stupidity: Particularly jarring in Thing Thing Arena 3, when mooks will rather try to shoot you through the wall/floor than walk around it to get a clear shot.
Also, everytime you see a mook with proxy mine launcher, expect him to blow up himself and/or his companions.
Awesome, but Impractical: The arrow gun in Thing Thing Arena 3. Sure, it shoots arrows. But they're about as weak as a standard pistol bullet, and you can't dual wield them.
BFG: As a result of the characters having wierd proportions, the weapons they use are often larger that they are.
If this game from the same producer is any indication, Thing-Things are about three feet tall, and the hands are the same size as ours.
Boom, Headshot: From Thing Thing 2 onward, killing an enemy exclusively with headshots causes their head to explode (In Thing Thing 2 itself, body parts explode when destroyed, so their head will eventually pop regardless).
In addition, the enemies survive until either their head or their three midsection parts are destroyed, leading to situations where you be chased by a dude consisting of a head, an arm and a pair of feet.
Mook Maker: Pretty much every area in Thing Thing 4 has one. It's never really described WHAT they are, but they nevertheless send wave after wave of Mooks at you.
More Dakka: The Jackhammer is an automatic shotgun which fires 5 pellets for every press of the trigger, and has the second highest fire rate of all the guns of Thing-Thing Arena 3, only second to duel wielding the the Glock 18c.
Unfortunately, damage per shot is rather dismal compared to the other shotguns in TTA3. It won't stop you from hosing down everyone you meet however. The achievement for 100 kills with the Jackhammer is appropriately called "Buckshot Firestorm".
Offscreen Teleportation: Particularly jarring in Thing-Thing Arena 3. Enemies have to keep coming from somewhere to attack you, otherwise the game doesn't work. But it gets ridiculous sometimes, when enemies spawn behind you when you move the camera ahead a bit.