http://bugs.winehq.org/show_bug.cgi?id=32302
--- Comment #18 from Vincent Povirk madewokherd@gmail.com 2012-12-11 10:29:22 CST --- It's a Unity game, so it's not a custom Mono. I don't think Unity puts anything special in their Mono build, but I could be wrong. Parts of Mono are LGPL so you may be able to contact the Endless Space devs and/or Unity devs to get the correct version and/or source code.
My hope with explicit-null-checks was that it would create a managed exception and thus get you a managed code backtrace from Mono itself. I wasn't expecting it to fix the problem. I guess this means the program is expecting a NULL reference and for some reason Mono isn't catching and translating the SEH exception properly. That would be the problem you need to solve, and a backtrace won't help with that.