What I would change?
I would simply do the games like before, with an integrated Steam-light client (if they dont want to use WON) so you can still launch the games with the normal game browsers like All Seeing Eye, GameSpy, Kwery (sp?) etc. Password and login would only be needed if you have Steam standalone for downloading games, mods, patches etc. People who love their friendslist and other stuff in Steam could simply still be using their loved Steam, while people who dont want that useless stuff simply used the game itself and their prefered game browser for playing the game.
I wouldnt limit the games to the newest versions. CS lost most of the good players and clans just because of that 1.6 forcing. Other mods even went poof because they lost fans because of Steam. And most small mod teams simply ceased to develop further because of Steam.
An extra program just to launch games from a single developer is simply stupid. Also the user friendlyness is nonexistent in Steam. Why do so many menus and unnessecary clicks to get into a game and why is the server browser so crappy? I didnt like the old Half-Life browser (thats why I used ASE, actually I dont know a single person who used the ingame browser) but this one is even worse by far. Then the bug that you cant assign the controls to any key anymore. That bug is old as Steam but has never been touched.
I am not talking about update programs like the one that comes with Neverwinter Nights, Sacred, etc. Steam is something completely different.
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I don't like arguing. Why can't we all just get along instead of fighting and arguing?
I have given up on waiting for BIS to come back to their senses and do a real ArmA 2 successor.