I have a suggestion for research. When you aquire a tech (through trading, invasion or stealing) that is out of sequence with what you already have (ie stealing laser 5 when you only have laser 1) I would like all intervening techs to be grayed out and not show up as available. The excection, of course, would be techs that have other branches. For instance, if you only have Space Militarization and you get Beam weapon theory, Space Weapons does not disappear because it also branches into missiles and mass drivers.