Yep old ideas Thanks for the point out.
How about mixing ideas-
- Old popular PC game -Leasure Suit Larry
- Body jumping and host control
- Micro settings
- Player evolution

So the player is a alien virus and is infecting a person. The virus controls the host to get 'it' to mate and spread the virus. Each person infected, infects others in a AI-sim. When the virus(player) enters a new host we switch to a micro setting and the virus must make its way to the host brain fighting off the hosts-body immune system. The virus(player) spawns a hybrid virus in the body. The virus(player) must enter some of the AI infected to absorb there hybrids and evolve it's self. The CDC is hunting the virus(player) to kill the pure alien source of the virus as all the other infected have human DNA-RNA hybrids they can treat. The virus evolves from making people sick to mutating them in to monsters, untill it has absorbed enough hybrids to mutate a human into it's alien source form.

You get 3d play(gta,watch dogs,ect), micro play(2d or 3d), player evolution(virus is a primer and player can choose it's final form through the choices of hybrids it absorbs), and go old trying to get laid(digital pick-up lines..need I say more?) all in one game.