A good choice for skirmish is Rogue planet
http://www.wargamevault.com/product/139359/Rogue-PlanetThe rules are designed for a fantasy sci-fi setting (such as a grim dark gothic future) But do not have any background or setting to stop you using them for any setting, period, or style you wish.
Like his last game, mayhem, the rules allow you to use any model or weapon you wish by letting you write your own profiles for your models.
I sadly have not been able to actually set the game up and play, as my games room has had a hole in the roof for ages now, and its not really usable! But I have read the rules, and made some profiles for some small skirmish teams.
It works well for any scale mini as there is no measuring for movement. There is some talk on lead adventures forum for adding a movement mod, but I dont think it matters that it is not in there, it works as it is.
It feels like a mix of necromunda (the setting, the campaign rules, etc..) but seems to play more like Inquisitor (more story based, then luck/dice base) Which is to say you will get more out of this game with a bit of roleplay/story telling. So probably not suitable for a strict tournament scene, this would play well for friendly/solo play.
Its dirt cheap too boot, and you can even use it with fantasy settings, though he is planning of making a complete fantasy version in the future.