When you take the setting of Siegecraft and combine it with the tower defence genre you get Siegecraft TD. The single player game is about holding back the Lizard army; the story is told through conversations before each level. The story is barely there, and in the end is inconsequential given that every level is the same. Starting off with a crossbow tower you quickly unlock the usual towers that slow down enemies, area of damage attacks and so on. You can also upgrade your towers during the level. Because most of the levels are in an open field (give or take a few small structures) you'll find yourself directing the path of the enemies by placing towers and fences to create bottlenecks. For the most part you can pound on the enemy until they throw stronger creatures that soak up the damage. Early in the levels I found myself overlooking the flying enemies that will just fly right across the map if you don't stop them, so keep an eye out for their flight path and keep some crossbows around there.
Working for and against Siegecraft TD is that it's a good tower defence game. But against it is that there isn't much to make it stand out amongst the other ones out there. The 3D field and the ability to move the camera around is cool, later on it also helps see around areas that aren't just flat fields.
While the tower defence part of the game never strays too far from the standard stuff for the genre, the game does look great. The 3D character models and levels are more detailed then you would think necessary but they do it. The gameplay is also well done. As much as it doesn't change the formula from similar games, they have at least refined it a lot.
Multiplayer is the mode that adds more to the game than other tower defence games. You can either go head to head or against several sides, fighting over several provinces and defending and invading territory to come out the winner. There is a lot more to do here than the single player mode, although you might have to wait for other players to take their turn. The tutorial seems to be broken and crashes the app which makes things harder than they need to be. To get the most out of this game you'll likely be spending most of your time here once the fairly short single player content runs out.
Siegecraft TD on one hand is a tower defence game like most others - although it looks good and is well made, it doesn't add anything fresh. On the other hand there is an interesting multiplayer mode that tries to do something different, but it depends how much you enjoy playing against other people. The game could've benefited from adding more elements from the multiplayer mode into the single player to give more to do. Check out Siegecraft TD if you want a polished tower defence game you can play against friends.