I finally managed to try out Xenos Rampant which I've had since Xmas. The game should actually have taken place several weeks ago but a combination of work being really busy and an assortment of bugs meant it kept getting postponed.
The rules use more or less the same format as the other Dan Mersey 'Rampant' rules... units are generally 5 or 10 strong and have 10 attack dice until they drop to half strength. Each unit has an Armour rating and casualties need to reach a multiple of that number before they take effect. If a unit is successfully shot at (even if there are no casualties) they need to test for morale. All very simple and dead easy to pick up.
As this was our first game I only added a couple of upgrades and special rules... one unit had armour piercing weapons and one of the vehicles had indirect fire etc. This, along with a simple encounter scenario may have made it a bit uninspiring.