Although this video is focused on Warhammer 40K, I think the techniques shown for building terrain entirely out of cardboard are worth studying.
The Miniature Wargaming Editor
Faction Wars Science Fiction Skirmish
Fire and Forget Games has released a downloadable PDF version of the rules for Faction Wars, the sci-fi skirmish game. The free 40-page PDF contains the basic rules of the game, sample squads for two factions, and a couple of scenarios to get you started.
Minifigz Lego Combat Rules
Minifigz is a set of rules for combat with Lego figurines.
Elfball Fantasy Football Rules
From Impact Games, Elfball is a set of fantasy “football” rules. It’s played on an oval field, so it’s not like “American Rules.”