Reference material:
Eclipse: https://www.fgbradleys.com/rules/rules4/Eclipse%20-%20rules.pdf
Dominions: http://www.illwinter.com/dom4/manual_dom4.pdf
Endless Space 2: http://cdn.edgecast.steamstatic.com/steam/apps/392110/manuals/ES2_PC_OM_210x297_UK_LR_V5.pdf?t=1496065741
Other 4x games: https://en.wikipedia.org/wiki/List_of_4X_video_games