I must say that I hate the fact that aliens can just trapse all over my territory. I've got Drengins and Altarians shooting it up right next to planets of mine because they are on opposite sides of my territory. I think that alien civilizations should not be able to send any ships into my territory unless we have made some kind of diplomatic agreement to that effect. Diplomatic relations should have levels which include the ability to send traders at one level, survey (unarmed) vessels at another level, then armed ships and troop transports only when a full alliance is established. I'd even recommend that the ability to send armed ships and troop transports be done only at the very highest level of alliances. It is difficult to defend your territory when the enemy can plant warships anywhere within your territory without repercussion. It would even be nice if you could charge aliens for their transit through your territory, much like countries do here for aircraft transiting their airspace. Again, this is a terribly annoying facet of an otherwise immensely enjoyable game.
