You can now cross over any two games series - which two would you chose?

Sins of a Solar Empire with Wing Commander. Play the strategy game then, when you need to, jump into a ship and help with the battle directly.

Jagged Alliance 2

with

Dungeon Keeper 2

Empire at War with Battlefront 2. The best of both worlds, strategy and first person shooting.

Wow.  That would be really awesome.  Great idea for a series. 

Mass Effect + Baldar's Gate II (i.e. Mass Effect played in the Baldar's Gate Style).

Absolutely brilliant.

I'd love a crossover between the gameplay of dungeon keeper and any mmorpg. One side plays adventurers, the other the overlords that construct dungeons and lands for them to visit.

GalCivII + Homeworld. I pay top dollar for it... 

Ryat and ZombiesRus5- Thats awesome!

(Would like to cross more but I'll stay on topic)

Kings Bounty and CIV IV

EWoM  and MoM.

Jak II and Metroid Prime. I have no idea why.

^ *shakes head*... That sounds ridiculous.

AAAUUGGH!! METROIDS!!!!

I would suggest Battlefront 2 and Halo (any kind) (I like the customizability of Halo and the third person views and Weaponry of Battlefront.)

My choice, which is weird.

Kohan cross Granado Espada (for the artstyle)

Would have Kohan-style gameplay with a Baroque-style art and units, along with magic.  It the game had Stardock-level AI, it would be a masterpiece.

Console pick:  (this is going to be really strange)

Virtua Fighter cross Buriki One

One of the most strategic games ever (yes, it's a fighting game, but it is very very strategic) which lacked some soul, combined with an obscure SNK franchise, which would be suitable to that style of game, yet had characters with plenty of soul.

Super Smash Brothers Brawl and Jump! Ultimate Stars.

Would be the most epic game in the universe.

Oh dear... this is basically the basis of all my game wants.

Empire at War Phoenix Rising mod and X-Wing

Sins and Homeworld

Supreme Commander and Company of Heroes Blitzkrieg mod

Star Wars or Star Trek and Eve Online

Command and Conquer and Mass Effect

Force Unleashed and Republic Commando

Sword of the Stars II and Outpost 2.

I haven't heard of Outpost 2 in a long time. And yeah, a good mix there.

Builder games are at their best when the game has a way to properly measure your success. And war is a very comprhensive way to do so.

Adding Battlefront 2 Extreme mod and the rest of the X-wing series to that would be the ultimate Star Wars experience!

I second that.

Ground control and dow2 would be neat. It would be dow2 but on a much more strategic level. Almost like that alternate table top game where every warhammer 40k unit is tiny as fuck.

Rainbow Six: Raven Sheild and X-Com.

BRB new pants.

Elderscrolls/MoM

Dig Dug and Pong... xD

C&C:TS and GalCiv3 (Because it has cloaks and really good multiplayer)  

Ship Designer works for ground units. Each planet plays on a 100x100 tile map and does not have to be fully conquered to move on with game.