Unless it changed very recently, you don't need to "activate" the game like you do for Steam games or other DRM using ones.

You only need to connect to download or update the game, once it's downloaded you can copy the game files and play on any computer. It's even very easy to make a "portable" version of the game(i.e. a version that can run from an USB disk.)

probably, but you need to log into your account if you want to update and download the newest patches. But, yes, I think that if you manage to download a copy of Minecraft, you do not need to 'activate' it to play offline.

Real warfare doesn't take place in turns.

Well you're comparing videogames to reality here, not me. Randomness in real-time game, that's fine by me, I can improvise. But such a massive deal of randomness you can only influence so little is infuriating in a turn based strategy to me. Wesnoth pretty much relies on save-reload mechanic, it's even got a bloody undo button in it's interface.

That's suppose to be for beginners... I used it very rarely, and only in campaigns on some of the particularly difficult levels. Also - It's not THAT random, the terrain the units are on matters a lot as well.

Natural Selection 2 - has many stuff that u mentioned: build-in tools, awesome gfx, steamworks... the problem is that the engine cant really render larger rooms then ~50m
0.AD - i had a lot fun modding this - simple xml files + collada for models. Not really next gen but the new version already introduced shader's and normalmaps... ah its a free opensource game.
Amnesia
Total War series
Civ4-5

Still no mention of JA2? Shame on you guys.

1) Available DRM free on GOG.com
2) Android version available, works fine on Wine, not so sure about a native linux port.
3) Tools available both for 1.12 and 1.13, with 1.13 being more user friendly
1.4) 12 doesn't have that many video options, 1.13 adds a few more, though don't expect anything fancy like bloom, hdr etc
5) See above
6) Source code available, though you still need the assets.