I tried both methods to reinstall VCRedist. A dual boot would be a solution and it actually wouldn't be such a big effort, but whats bothering me about that is, that I can't install Windows XP, which would be a much better second system, because of some old games, which doesn't run on any NT6 based Windows. But there has to be some kind of solution, to get Mass Effect 2 running on my system, if Windows 10 is installed.
But you're right, it is kind of strange, that it works perfectly with Windows 8.1, but doesn't even start with Windows 10. If I remember correctly, I played Mass Effect2 on Windows 10, back when 10 was released. But some reason I often have such kind of luck with a Bioware game. First with Dragon Age II which was stuttering like hell on a system, which should have been able to play the game with the highest settings, then with Dragon Age Inquisition, which I had exactly 8 month, before I was able to play it (and no, the problem was my system), then with Mass Effect 3, which crashed severeal times during the game, sometimes at crucial points in the game. And now the problem with ME2. Maybe I'm just cursed, if it comes to Bioware games, but I really love them, so I just have to keep trying.