Well, true enough Sir_Schwick. I think I would prefer it if it was a 'semi-random' end of sorts. Perhaps, as you suggested, once a certain number of modern-age techs are researched-by a certain % of remaining civs-then the 'end game' clock comes into effect (with a starting number determined by the RNG) At this point you KNOW the end of the game is coming up-you simply don't know exactly WHEN this will happen!!
Alternatively, player(s) can choose to retire at any point in the game, at which time victory conditions are calculated.
This then also brings us to the issue of HOW the game is won. I have a REAL problem with 'single victories' bringing a game to a head. I would rather see the game end at a 'semi-predetermined' time, as stipulated above, and then having ALL selected victory conditions calculated at this time. Whoever wins the MAJORITY of victory conditions is the ULTIMATE victor of the game.
Possible victories are the culture victory (mostly as it stands now), and the economic and scientific victories (which would work along similar lines to the culture victory). Additional victories might include:
Diplomatic Victory: would be determined on a points basis, calculated on the terms of the number and type of diplomatic agreements you have made throughout the game, as well as the extent to which you have honoured them. Points would also be won according to your current international standing and according to your current 'morality level'. Points would be deducted according to your current 'atrocity rating'.
Space Race Victory: After your first 'space-based' small wonder is built, you can launch a variety of different mission types into space. Success chances will vary according to financing, mission type, specific improvements/wonders and tech levels-and different missions will gain you varying numbers of points. The player with the MOST amount of points wins the space-race victory.
Domination victory: will be determined, first and foremost, by the amount of population you currently control. Lesser points will then be awarded according to the number of cities you control and, lastly, the least amounts of points will be awarded according to the % of land mass you control. In addition, points would be awarded according to the number, and size, of protectorates/vassal states you have associated to you.
Religious victory: Points are awarded according to the number of people who belong to your religion, and bonus points awarded for every city which belongs ENTIRELY to your religion. If your state religion is that of another civ, then you can win an 'allied victory' in this category.
So, in all, you might have a total of 7-8 different victory types, and the nation who has the most will be the ultimate winner. If a tie eventuates, then final victory will come down to demographics and/or histiographic factors between the tied civs!
Anyway, thats at least how I would like to see it happen!
Yours,
Aussie_Lurker.