STRAFE is a game that gets at least some flak due to the fact it's not really an old-school game in the same vein as Doom or Quake. It's good on its own merits, but the advertising (which I haven't watched so my info on it is second-hand) apparently gave people the impression it was going to be like Doom or Quake.
But that's not why I'm bringing it up.
In STRAFE, you can only have one permanent weapon - your pick of a railgun, shotgun, or machine gun. Other guns only have about one clip's worth of ammo in them, and, when depleted, your character adjusts the way they hold it so that they can swing/throw it, whereupon it breaks or, in some instances, explodes.
This swing/throw inflicts a lot of damage - my advice is to not use it on anything less squishy than the Icarus's ranged enemies, 'cause it'll pretty much kill them in one hit.
Also, it's the act of using your gun as a club so hard it breaks upon impact and can one-shot enemies that usually can't be one-shotted without an explosive coming into play. I guess I'm a sucker for silly yet effective violence like that.
I think Borderlands (or maybe Borderlands 2?) had at least one gun that you could throw like a grenade, only for the gun to be digistructed (basically re-materialized) back in your hand.
Now, in Paint The Town Red (At least, if the demo is anything to go by), you can pick up just about any weapon and swing/throw it into an enemy's face.
Just like the STRAFE example, this is quite similar to another more well-known game - Dead Rising (maybe not 4, but plenty of people seem to hate 4 anyway so I'm fine with excluding it). As in PtTR, Dead Rising lets you pick up all manner of things (skateboards, golf clubs complete with golf balls, later on you get metal baseball bats that hit baseballs at enemies rather than a normal swing, etc.) and use them as weapons, often with a surprising amount of effectiveness.
Finally, Fistful of Frags lets you throw guns at enemies with the selection of a very cheap loadout perk. The throw has its flaws - you need to charge it up, namely, and you lose your weapon(s) when you do let fly - but its damage is good and you get plenty of points for kills using thrown guns - and you can even pick them up afterwards!
Long story short, I want a game with all these mechanics. It'd probably be a hell of a mess, but I think there's room in a at least somewhat saturated market for a game like that - an action game where all pieces of your equipment are not temporary so much as ephemeral, and discarding your gear is as important as selecting and using it.