I've been playing a bunch of Revenge Of The Titans, which is currently available in incomplete form via demo, and also via slightly more complete pre-order beta access at half price, I think? Yes, that seems to be the case. Anyway, there's something about it.
The game is a variant on traditional tower-defence designs, with a base towards which an army of aliens march, and lots of defensive technologies that you can place along their path to fight them off. As you play you also collect resources from clusters of crystal that are distributed across each map, and these are the primary way to make money, with the destruction of the titans themselves also giving you a trickle of cash.
The game starts on Earth, and heads off into the solar system as you defend your way through various stages of alien invasion, with the titans themselves becoming more fearsome as you play. Between levels you can choose to spend some of your budget on research - unlocking research options which then allow you to unlock forcefields, physical defences, and various tiers of offensive tower.
Where Revenge Of The Titans perhaps differs from most tower games is that it's heavy on the micro-management. While you have to place refineries, towers and other defences, you also have to click to pick up your resources, click to reload towers, and click to collect cash and other bonuses that are dropped during play. This actually makes the game fairly hectic once you get past the first few levels. I've found this interesting, because it gives you an extra tier of involvement - a bit like the sun collection in Plants Vs Zombies. Combine this franticness with the beautiful, minimal art and general ambience, and you have a mixture that I find rather compelling.
But there are some weird things I'm not entirely comfortable with. One is that it's possible to get yourself in a bit of a hole long term, because the research costs rely on you not spending too much as you play. If you're a bit free with the turret construction - as I tend to be - you're actually making things harder for yourself down the line. Puppgygames are tweaking this stuff right now, so I expect a really good balance by the time the final version arrives, but I can't see it being entirely expunged, and it's been a mild frustration up til now. Related to this, I wish there was a little more clue as to how the tech tree is structured, because without playing the game through several times, I can't really work out what I am aiming for techwise.
The other weirdness is that the levels are randomly generated. This means - thanks to the layout of the roads that funnel the titans towards you, and the location of the crystals on the map - that one generation of a specific level might be easier or harder than another. In fact, when I got really stuck because of the lack of funds I mentioned previously, I ended up restarting one level until it gave me a favourable defensive alcove amid rocks, one that was easy to hold against the incoming hordes. It's an odd thing to be able to do, and felt a bit cheaty.
Anyway, play the demo, see what you think. I suspect there's a certain kind of RTS player or tower defence junkie who will, like me, get a kick out of it. I've been putting a load of time into the beta and I'm genuinely looking forward to the final release.