The most complex action in Paradox grand strategy games (Europa Universalis 4, Crusader Kings II, Victoria 2, Hearts of Iron 3) would be dragging boxes around units, while possibly holding down shift or similar as a modifier.I can use shift and space bar when using the mouse. It's multiple keyboard keys at the same time that I struggle with eg. running and jumping at the same time while maintaining direction.
The games are difficult from a gameplay perspective, but from a control perspective they're very simplistic.
Crusader Kings II has a demo you could try. It can be downloaded on its Steam page: http://store.steampowered.com/app/203770/