What crossovers would you make?

Total War: Vice City

Crusader Kings II: Beyond the Sword

Counter-Strike: Arkham City

Left 4 Portal 2

And "Dear Esther Theft Auto" because why not?

The Elder Alan: Katareka

Grand Sims Auto

Don't STALK(er) - Fallout Wars

Mortal Kombat vs. Street Fighter... because why not.

Dead Island - Pokemon

Secret of Bad Fortix!

Injustice: Mortal Kombat among us

Assassin's Cry 4.

Guns of Icarus Online: Total War

Skyrim:Prepare to die Edition

Dark Souls:Wrath of the Dragonborn

Left 4 Walking DayZ.

Fantasy Kombat ( Mortal Kombat + Final Fantasy.. older FF games not the newest ones. )

Grand Theft Evil. ( GTA+Resident Evil.. old resident evil games not the new ones. )

Sleeping Dead. ( Sleeping Dogs+ Walking Dead, or Sleeping Dogs+some other game involving zombies such as Dead Island :P )

Saints Row the Masquerade. ( Saints Row+ Vampire the Masquerade. Or have it with GTA instead.. either one really. )

Might come up with others later.. trying to avoid copies of other people here but I think I already made a few by accident ><

Warcraft/Starcraft.

Do not starve

Assassin's Cause.
TrackMidnight GRID: Showdown
Dead Island Space Rally
Orcs Must DOTA
L.A. Noitu Love 2
Half-Left 4 Deadlight
Team Fortix
Spec Ops: The Line Rider
Deus May Far Cry
Dungeon Hearts Party Defenders Siegeland of Dredmor
Payday Nightsky at the Inventory

Sexy Potato Potato

XCOM: EU + Mass Effect.

A buddy once wanted to play Guitar Hero: Rockband with me... i responded, that i'd rather play Counter Strike: Modern Warfare with him

Knights of the Old Dragon Age Mass Effect Republic.

Tomb raider + Starcraft

Street Kombat

Killer Instinct x Mortal Kombat

Gears of Halo Theft Auto 6.

Mortal Mario Kombat