I've long had a small collection of 15mm sci-fi miniatures painted up for skirmish games. Then, last week, Andrew gifted my some 15mm sci-fi scatter terrain and a few bunkers and other small buildings which now allow me to future-up my ancient city Antiocheia Mikros. So, this week, I set up a table (along with my son's Slave One toy with is roughly to scale) and tried out a few turns of Grimdrak Future: Firefight by Gaetano Ferrara. The rules are freely downloadable and seemed simple, but effective. They are written for 28mm miniatures, so we swapped out inches for cm to convert to 15mm figures.
I took a force of smugglers/rebels, while my wee lad controlled the Imperial Night Watch special forces. The rules are very definatley geared to the GW futuristic game set in the 41st millenium, but the force lists are pretty flexible allowing you to build most generic sci-fi tropes.
I played more aggressively than the wee boy and took most of my forces through the alleys and the landing area, leaving only a sniper on the rooftops. The lad took up a pretty defensive position and shot at me. A lot.
Although I managed to take down his trooper packing a grenade launcher, the storm troopers were handier with their blasters and took down my fluffy humanoid alien and two of my assault-rifle wielding fire team.
We only played four turns, but everything seemed to work well mechanically. Lots of shooting took place, we had quite a number of hits, but not a huge death toll. That is a good thing in my books. For a rule set that, all up, covers two pages, these were pretty damned impressive. I'll certainly play again.