My thoughts on Castlestorm:
You'll be playing the good guy knight who's charged with the heroic task to defend the king's castle from the evil attackers. To do so, you're given four tools: an army, a ballista, yourself and the castle.
Let's start with the castle editor. You'll be given a set of pre-made castles that you can use or edit, but you can also build your own castle from scratch. To do so, you have several rooms, each representing a certain kind of soldier or creature that may only be used in battle if its room has been built into your castle. More rooms are unlocked throughout the campaign, and you'll have some sctructures for visual und defensive purposes.
During the campaign (or multiplayer) you can now use all those units whose room you've added to your building to fend off enemy units. The are knights, archers, birds and dragons, rock giants and other cool stuff to throw at your enemies gates. The stronger the unit the more expensive it is, so summoning the right amount of them and the right composition is crucial.
Speaking of throwing: Your ballista does not only shoot arrows but can also be equipped with rocks to damage the enemy castle, rainbow farting sheeps, exploding apples and several other things to defend your gates. At some point I felt like the ballista was too strong of a weapon because if used correctly it can kill some of the most expensive units by itself.
If things get harsh you can summon one of several heroes onto the battlefield, controlled by yourself, to slash through the enemy troops. After a certain amount time or once your hero dies you'll be back to shooting the ballista and summoning units.
The game is won/lost, once an army has managed to either break into the opposing gate and steal the flag, or a castle has been destroyed to the point where no room is left and thus no units can be summoned anymore.
Throughout the campaign you'll have some limitations, like you'll only be able to use the ballista, or you may only use soldiers, but that's as far as variety goes. There are some levels with a special boss, and some where you have to fulfill a certain task, but that's it.
Each level gives you gold depending on how well you perform, and you'll get some extra gold if you could complete a challence like never miss an arrow, let the flag steal by a certain kind of unit and so on.
Most of the time, there is nothing special though. What makes the game so addicting is the joy of hitting a headshot with your arrows, the fun dialogues between the levels and the several unlocks like new rooms or even a new race (is exactly the same but looks different).
Graphics are good and so is the music. Okay game for killing some time, not good if you plan on playing it for more than two hours at once because most missions feel the same.
Buy it when on sale!