OpenLieroX.pdb is needed so that the automatic crash reporter works.
Automatic level download should work in most cases. Only requirement is that it is uploaded in Filebase. So all those level can savely be removed -- when you join a server (even when the game has started already), it should work. However, it might be a bit buggy sometimes. (Multiple bugs where already reported).
Automatic mod download doesn't work yet. While in lobby, manuel download (by clicking on the download button next to the mod) might work. Probably even more buggier though than the level download.
These both features where planned as mandatory for such a minimal version.
Error: Whenever I try to start a game the whole thing crashes, then it brings me back telling me that it crashed. Anyone know why this is happening?
Probably you removed something what cannot be removed. However, the game should never crash. Do you still have the openlierox.pdb in that directory so that the automatic crash reporter works and sends us the information about this crash? Otherwise I cannot really tell. I also need the log file of course.
You cannot really remove anything except maps, mods, skins and themes. (Well you spoke about the dedicated script and other stuff but they are maybe 1kb or so, also it would not be possible to use the ded server in that case anymore.)
We planned such a minimal version a few times. But there was never very high (or any) request for it yet and so we considered it as not that important.