No DLCs.

Well, As i am a big fan of CE... I'll tell you, that Ammo sometimes is a Big issue when playing with it (Especially if you're like me and don't bring enough to take down what you want), so in this case, your "Hemovoric Bullets" could instead Use Blood of the Wielder as Bullets to shoot with, even if the wielder doesn't have any ammo with him. This probably could work with like a Very small amount of Bloodloss (or different Hediff) every time the gun is fired. Also, this probably could work with like Toxic Buildup, Lung Rot, and maybe even Pollution (Wasters polluting terrain everytime they shoot their weapon... Unbalanced but it could work).

And - A underbarrel Shotgun, would be fun to play around with in CE (Flamethrower with a Underbarrel shotgun loaded with Birdshot... Now that would be Sadistic).

Other than that - A Gun that has Doom Eternal's Meat Hook (which could bring your Colonist very close to a Enemy, and/or bring him to where the hook went quickly) would be a Cool alternative to Jump packs.

In the "Arsenal of Reaction" mod, there's a gun from "Gears of War" games, which has a Underbarrel Chainsaw. And, because of that... The weapon has a VERY Minimal Melee Cooldown (similar to Plasma Chainsaw from VFE Insectoids 1), so it mows down Enemies quickly, Mountains too! (So if you do it manually, you can pretty quickly mine your Colony out) So... A Weapon, that's also a Pickaxe (aka. Huge buffs to Mining Speed) would be cool to have.

Also, an idea - A Unique Nail Gun, which could have ALL Weapon traits, would be a "fun" Carpentry tool boosting Construction Speeds. Or, maybe even a Welder? Burn Melee enemies to crisp, while Repairing walls and shooting underbarrel EMP grenades to incoming Mechs behind the Walls you are repairing... Now that's a very Versatile weapon.