This is actually very true and triggered me - we play a lot of Terraforming Mars, always "as intended". I know it has a single-player mode, but I think that should lend itself quite easily to do as a cooperative game as well! You'd have to make some minor changes. I wonder if the maker will come up with this at some point!
 

Well in TM, the single player goal IIRC is to complete the terraforming by turn X. You could make that the goal in multi-player too. But I played 2 (competitive, non-advanced) 5-player games of TM just last week, and both were over on turn 7. That doesn't give a lot of leeway for setting an appropriate goal, it would literally have to be turn 6. It would probably work better in advanced mode, which takes longer. A lot more cards would become bad/useless (VPs), as well as mechanics like the Awards and Milestones without much more tweaking.
 

Thanks for brainstorming! Perhaps an easy way is to do it differently: finish the game on or before turn 8 with a minimum of (say) 800 points combined. As an extra action, you are allowed to trade one card with another player at the start of your turn. That would encourage people to optimize and specialize during the game.