SQUAKE has a virus?

Gen.Trojan.Heur

That means it's a generic heuristics detection. Heuristics is an algorithm that AV software uses to find malware that is not yet in their database, it looks at the way certain applications behave and decides if that application is potentially malicious.

SQUAKE seems to have ticked a few boxes in their Trojan list, but it will almost certainly be a false positive.

It happens to me every once in a while too with different games, they are always false positives (I hope). I just let the developer know on the forum and they report it to the antivirus company.

I have Kaspersky and it found no virus on the game.

Upload the .exe here: https://virustotal.com/

And check the results, if NOD32, Kaspersky and other good AV software does not detect a virus then it is a false positive. In that case, report here: http://www.bitdefender.com/submit/

I'm using the latest version (9.0.408.1) of ESET NOD32 and have had no warning to date.

Its a false positive. I'm playing it since a week without problem and none virus detection.

I honestly feel sorry for anybody that produces games through Game Maker / Studio, RPG Maker, and many oter "ready-made engine" setups, as they tend to trip the most false positives and thus garner a lot of bad PR. Something similar happened to Risk of Rain long ago and a particularly charismatic (read as: loud and obnoxious) user almost got it removed from Steam when Kaspersky was tripping false on it.