Since i'm not very fund on this setting.... can you suggest me some nice rulesets for small battles?

i mean i would like something beyond simple miniature boardgame, but something easier than a Gurps setting, with each player controlling 1 character.

For adventures that could range from alien to spaceship troopers, or even mass effect.

I'd like something with nice tactical fighting rules, fast character generation (i have to tempt my friends with some one-shots^^) and open for out of combat roleplaying!^^

I could have used Gurps but i must say it's totally unfriendly and the char generation takes a lot of time!^^

So... Are you looking for an RPG, a tactical (and customizable) minis game, or something in between?
If it's an RPG, you may want to look at:
Savage Worlds (open-ended character creation system that has a free-for-download tactical miniatures game expansion);
Mutants and Masterminds (supers-based RPG based on the d20 system, lots of options but tactical maps can break down with even minimal levels of movement powers);
BESM 2e (out of print anime RPG, designed to cover a lot of different genres, should be able to find one without too much trouble; 3e not so much);
D6 Space (sci-fi based system based on the acclaimed Star Wars D6 system by West End Games. Not sure if it's in print, but you should be able to easily find a copy);

As for miniatures battles... Honestly, I don't have nearly as much experience with those as I'd like (particularly the customizable ones where you stat out the minis you have instead of build the minis to match the provided stats). The ones I know about are:
Infinity: Sci-Fi miniatures game that features squad-based tactics. Haven't played it or read the rulebook, so I can't tell you any more than that.
Necromunda: squad-based miniatures game based on the Warhammer 40k setting. Again, this is one I haven't played or read the rulebook for, so suitability may vary.
Warhammer 40k: Grim and gritty sci-fantasy, unfortunately all the rules only support the official miniatures. Can be very expensive, but there's a variant for running Kill Teams that could be used for what you want without the cost of building up a 2000 point army.

Hm... That's all I can think of at the moment. Hopefully others will come on and fill in the gaps that I missed. Still, plenty of stuff for you to ponder on.
Magius out.

2 Hour Wargames has 5150 star Army. While it is more for small units and up at the moment the single fig expansion is due out next month. Both have rules for troops to get better.

i'm reading no limits rulebook (24 pages atm) and it seems nice, i have to see some templates for the "character" miniatures to see if it fits the idea of giving 1 model to each player...
Anyway it's still a miniature game.... so.... great for one-shots (or encounters-style campaign) but it lacks rules for roleplaying.

i think i'll have to decide...
if i want a roleplaying sci-fi campaign maybe i'll go for star wars d20 (scrapping away jedis) if it has to be a "filler" when we don't have the legal number for our main fantasy campaign.... then i think i'll go for no limits!^^

I would highly emphasize a vote for 'Savage Worlds'. This is a great system, and they just released a great 'Deluxe' edition that makes it even better.

http://www.peginc.com/

They've even got a test-drive version of the rules you could try:

http://www.peginc.com/Downloads/SWEX/TD06.pdf

It's great for any setting we've tried it with, and works great for both Roleplay and Skirmish up to battle level rules. Also includes great chase and prolonged action rules.

at first sight savage worlds seems more for a post apocalyptic setting...

something like fallout....


i'd like more something like starcraft starship troopers ghost in the shell....

i like inflitration missions, defending against hored of aliens, conquering and or defending bases, the presence of droids from little to big ones, being able to use vehicles...

Savage Worlds has rules for large battles, and is built to be quick an easy for facing hordes of creatures. We played a 'Space: Above and Beyond' campaign, which not exactly what you're talking about is much more 'heroic' in scope. We did everything from ship to ship space combat down to skirmish level combat on planet surface, to slogging through a base filled with enemy.

I wouldn't discount it as being set for any one type of setting.

To throw my two cents in, I think from Margaret Weis Productions is a fun system. I first learned of it with the Serenity RPG - Cortex is a generic set of rules which several of the MWP games use.

Check it out!

The current offering of Gamma World? Not exactly what you're looking for but great fun all the same...