Been on a tower defense kick recently -
Tower Tactics Liberation - roguelike tower defense, unlockable decks, kinda futuristic space themed. Got a lot of mileage out of this one, good quick fun. No mazing for this one, just placement on pre-generated tower locations, although most maps have more than enough pre-existing positions for almost any tower combo. Still some balance issues ( holy guilds deck is sooooo bad ) but good fun regardless. Early access tagged, but a finished game regardless, the dev just adds random stuff as time goes by.
Spirits of the Hellements - hex based fantasy tower defense - pretty innovative 'towers', they are all 'spirits' that have several different upgrade talent trees that change them in pretty drastic ways. For example, one of the towers is a myconoid village - you can set a spore trap on an adjacent lane, and they have archers that shoot at fliers in a fairly large range. Out of the three talent trees, one of them lets them shoot at ground targets and either fire their spore traps on top of their arrows, or makes their spore trap create a huge persistent cloud that increases damage taken and also lets other mushroom men shoot things inside it, even if they don't have the shoot at ground upgrade. Another one lets you build more traps at further distances, and then increases the trap recharge for every trap on the map. Then on top of that, they also get special abilities when they are built on a 'Hellement' that vary based on which element it is, and how much you have upgraded that element on that map. ( Every 5 waves you get a challenge wave where you can pick a combination of bonus and penalty, e.g. upgrade all fire hellements and elite monsters get health regeneration etc )
Decent graphics, satisfying effects with the mass carnage I like to see in tower defense, and original, in-depth tower designs and upgrades.
Downsides is that it is very easy - there's a lot of powerful synergies you can use that quickly become overwhelmingly strong - I wouldn't consider playing it on anything other than the second hardest difficulty even if you were new to the genre - veterans should start on 'Diablo' difficulty.
No roguelike elements or meta-progression ( well, tower talent tree unlocks, but you can do them in any order you feel like and there's no grinding for them, just playing the normal maps), so is an easy playthrough and done in 30 ish hours on the hardest difficulty.
Dungeon Warfare 2 - physics based meta progression one with levels, talent trees, diablo-like equipment, trap skill levels etc. Pretty primitive graphics, but good fun if you like pushing armies of adventurers off the edge of a cliff into lava, or having harpoon traps that shoot cabled harpoons into people and then drag them into pits. Has a bunch of campaign maps, as well as procedurally generated maps of arbitrary levels, as well as letting you reset your level/gold/items to restart the campaign at a higher difficulty level, while keeping the trap bonus you got from completing the campaign maps. My only real complaint is that battering ram enemies being virtually immune to every form of crowd control makes a lot of the fun traps kind of pointless at high levels. ( You pretty much have to kill them with pure damage traps, which is annoying ).
