Astral Conflict 2.0 Quick play, skirmish-style rules with custom ship builds Review - very nice freebie. Good depth without becoming too complicated. More for a veteran gamer than a younger or inexperienced wargamer.
Raze the Castle! Each player controls a castle and small town in a fantasy setting Review - Free games are great. 3 pages of rules and 3 pages of tables. Just add dice and paper and pencil. Seems best for a number of players.