Resident Evil and Carmageddon. Running over zombies while shooting them would be freaking awesome.

Resident Evil is Survival Horror....can you run out of gas?

Yes, but there will be suspiciously placed gas stations at each mile.

But with RE1 style controls, they'll still be plenty hard to park at

Baldur's Gate + Any game = Instant Win

I'd like to take a mix of the RTS genre and the Puzzle (twitch) genre.

Back in my console days I got the idea of a free-roaming JRPG with a Virtua Fighter-esque combat system set in the Streets of Rage universe.
Or here's another: A 3D non-linear third-person CRPG in the Shadowrun P&P setting with a combat system that combines a real-time-with-pause system with the Braid time manipulation mechanic, perhaps replacing the 'pause' feature with a rewind/fast-forward setup.

Baldurs Gate + Batman? Small party, Batman, Robin, Batgirl & Nightwing beating the shit out of a horde of supervillain henchmen. Yeah I think I could get into that

Or you could settle for Freedom Force... =)
Halo Vs Call of Duty, then you'd have a Halo game worth completing!

Exactly. Although it's hard to tell if it's the PSP they're ripping off as everything seems to be heading in a black, shiny, curvy rectangle direction at the moment. Maybe industry designer geeks are intending 2010 to be a tribute to Odyssey Two by flooding the world with little baby Monoliths?

Thief (Deus Ex * System Shock 2) = WIN.

Dark Messiah was something of a combination of Thief and Deus Ex. In a way...

Please explain as I have never played Dark Messiah.

So Warhammer 40.000 vs. its lite version ala Blizzard? Hell no.

Dark Messiah is a first person RPG with a character development is similar to that of Deus Ex. It has a wealth of combat options, even including the ability to hold your arrow to a flame to create a fire arrow, throwing jugs of oil to make areas flammable, kicking enemies into spikes/off ledges as well as various options specific to the environment in question.
You can make very good use of stealth in the game and have the option to craft quite a stealthy character. The environments are reminiscent of Thief and you are tasked with obtaining items of power.
You can forge your own weapons using blacksmiths' equipment (from melting down the metal, forging the blade then crafting the hilt). There are also some impressive set pieces such as a rooftop chase, surviving an attack on a citadel by a cyclops and battling dragons.