This is the fantasy adaption of De Bellis Antiquitatis, Phil Barker's celebrated ancients/medievals rules. "HOTT", as it's affectionately known, simplifies some of the troop types of the latter, while adding others to cover fantastic beings (e.g. dragons) and larger-than-life personalities (heroes, magicians, etc). The result is a simple but very versatile ruleset that can be applied to almost any fantasy setting, as well as the sort of science fiction where troops form lines on the battlefield rather than nuke one another from orbit. Some also use it for historical battles, but I prefer to stick to DBA for that.

Thanks to the co-authors - Sue Laflin Barker and Richard Bodley Scott - the 2nd edition of HOTT is written in a less dense and more easily digested style than most of Phil Barker's rules.