Originally posted by Beammeuppy
How do you plan to play until 2050 and build your empire in a controlled way while avoiding diplo AND space race AND cultural AND domination AND conquest. ... Yet I am open for suggestions!
Well that's the thing

It does actually add to the challenge to accomplish this. You can take out everything except one rival city, and box that city in so that it cannot grow or send units anywhere. Then you don't need to worry about the space race. You need to control the UN. You need to avoid taking too much (domination.) And you need to do all these things at once.
Efficiently taking out the last rival(s) without resettling the land is usually straightforward but can be interesting. (If it seems too easy, try it on a huge deity map with 15 rivals

When you get near 2/3 of the world there will probably be a number of strong rivals left. Taking them out without settling the remaining land can be a challenge.)
I've found that it adds a lot to the challenge to milk a controlled (i.e. just boxed in rivals remain, to make the milking stage fast) diplomatic victory. It can be done! If that is still too boring (try it before you decide

), try getting all six wins out of a single game (requires milking of course to include the retirement win), that's quite a challenge.
I don't think of milking as avoiding victory, I think of it as choosing the time and place of victory.
I find that the milking stage of the game is not nearly as tedious as one might think if you haven't done it. The boring part is adding a marketplace, hospital, and mass transit to all the cities. But even that doesn't take all that much effort. Optimizing growth and location is even less work but is more interesting. Ensuring that you don't get a cultural victory is less effort again. (Boring but quick and easy to sell off some stuff.) If you want to "beautify" the unused land (e.g. pull up unnecessary railroads and plant forests) that takes longer than any of the other parts. But that is of course not necessary, it doesn't add to score. The turns go very quickly in the milking stage. When there are just one or two rival cities with few units, and there is nothing left for the automated workers to do, the computer plays the turns quite quickly, no big deal.