Strike Legion is an excellent set of Sci-fi tactical combat rules. The scale is one stand equals a team and individual vehicles. It is designed for 6mm minis but easily scaled to 15mm. The game is reasonably streamlined but includes a huge array of options so players can choose the level of detail they desire as well as match the rules to their preferred Sci-fi genre. Everything from infantry to air support and artillery is covered. if you add in the other supplements there is no area of Sci-fi combat the rules do not cover. Physical presentation is very good as well.
If you have any interest in Sci-fi tactical combat Stirke Legion is a must buy. It also complements the excellent new Gruntz rules as well by offering a somewhat larger scope and more comprehensive coverage.