A bunch of games like Morrowind and XCOM (for Windows) require a simple patch to accept mouse and/or keyboard input properly. It's a very simple fix and might be worth adding to Gentoo. The linked bug report on WineHQ has 2 working patches, the one I mean is the most recent one by Ben Hall. Reproducible: Always
we don't try and deal in these kind of behavior modification patches anymore. wine ebuilds have user patch support, so put things in /etc/portage/patches/.