Villainous is a rare beast: The reverse tower defense game. I've only ever seen two other games in the genre; I've reviewed one of them (prosaically named "Anti-TD") here. (It's not impossible that I'll review the other at some point, especially since aspects of its "story" are very whimsical and appealing, but no guarantees.)
As the name suggests, Villainous involves playing as, well, a villain. As such, one sends out raiders to attack a succession of towns, and these raiders must work their way past the defensive towers surrounding said towns.
In the process, one collects "infamy" (money), both from the deaths of one's own monsters and from successful raiding, to improve one's castle, which is actually not so much a castle as a rather pretty visual indicator of your technology tree that you've purchased with your infamy thus far.
And therein is perhaps the best part of this game: It's got a lot of very neat little flavorful bits in terms of how it's structured and visualized. While the actual gameplay feels a bit unfinished and the graphics are relatively crude, the game is full of nice touches and things that make you feel kind of evil. It reminds me rather strongly of Tower of Doom, funnily enough. (Funny because there are essentially no structural similarities between the two games, just some minor flavor similarities.)
As with tower defense games, the raiders have a certain amount of variety; the basic "goblin" raiders are actually the only ones that count towards "raiding" in this game. The others are all intended to be meatshields for the goblin (such as the giant turtle seen here) or to provide defenses for the pack or enhancements to one's spellcasting abilities.
You can also cast instant spells to protect your minions; there are two that disable towers and one that heals minions. (The game's a little low on actual variety, which is one of its few real faults.) The disabling spells are rather crucial. The game has a rather interesting balance, in that you can purchase upgrades even when a raid is entirely unsuccessful, and losing a minion gives you the mana you need to cast spells as well, giving your other minions a better chance to survive. The spells have an increasing cost system, but it actually doesn't bother me as much here, because they start with such low costs you'd be able to spam them forever if they didn't increase; if they cost more at the start you'd never be able to start using them until it was too late.
Tower damage increases over time rather than the number of towers increasing (which is how it's done in Anti-TD), so eventually the towers will deal double or better damage, guaranteeing that eventually the raid will end no matter how strong the force you assembled is.
To return to the subject of the "castle," here's a look at the completed version.
Rather fun; I quite like the detail of the rainbow, which seems a bit incongruous considering this is an evil overlord's castle (but that only makes it better).
And with the full upgrade tree, one can manage some rather extreme overkill on the various early towns with even the most basic strategies, such as this 73-raids-over-the-gold-medal siege I did on a whim for the review.
The problem with the game, actually, is that once you've purchased everything, there's never anything new again (actually, there's nothing new for a while before that because many of your purchases will be upgrades to existing ones, and a lot of them are boring utility things like bonus hitpoints), and there's really not that much variety in the first place. There's only six kinds of raider and three kinds of spell, and it generally feels less like you're fielding a raiding party and more like you're building a raid-train. Which sounds terribly amusing, admittedly, but is rather boring in practice. I don't really mind the fact that only the goblin raiders actually raid in principle, but each type of raider is so specialized that it also feels limiting. I'd rather they all be able to raid, and then there's a specialized raider who gets double the money for a successful raid.
On the plus side, there's some decent variety in enemy towers, and said variety is such that it's basically always clear which enemy towers are the most dangerous and thus most in need of a good stunning.
Regardless, while this game's not perfect, it's a great concept (and honestly much better than Anti-TD), and deserves some playing. It really feels kind of like the prototype to a better game, though.