Sure, some leveling just gets you new hats and badges, or server vote tiebreak priority. I'm okay with that, but increasingly games reward paying and grinding, and no just free to play games on the first count.
I would like simply a resource of "modern enough" (for their context games, quake live still does what it sets out to perfectly) which are both available online in a legal manner and lack paying for advantages or a persistent leveling up system which has advantages. So, for example, DOTA's leveling up is all in one match and is thus a valid member of this list, but if you can buy advantages of any sort its not valid(not sure, don't play Valves Dota but old WC3 DotA would have been fine).
At least a paragraph of discussion on the games you mention would be appreciated just so we all know what its about.
Natural Selection 2:[Steam link] Finally looks like its premature release is at it's end and that the game is no longer in a beta quality, a very good beta it was too. Now it works more reliably! For those of you who were not stung by its early performance problems shouldn't need to worry either. Its a team versus team indoors "Marine" Vs "Aliens" shooter, early play is exciting an bewildering in equal measure as beast scuttle out of ventilation shafts and automatic weapons meet flying bird monsters, as you grow into the game you'll learn about the strategic level of resource conflict and countering technological advances. Communication is massively useful at a higher level but nothing stops you quietly following your own nose and trying to help.
SWAT3:[GoG Link] I'll be honest, I would probably have linked to SWAT4 but with it not being availably digitally its not really qualifying for this thread, but SWAT3 is no slouch being only slightly graphically inferior and while some of its situations are less dark they are no less plausible. Its a first person shooter where you don't shoot on sight, where you value surprise more than firepower and a perfect run has a kill-count of 0. You are police, but instead of polite old lady helping police you are shouty arresting policemen... You'll never be able to watch SWAT teams in TV series again without frowning and muttering "Thats not how you stack up".