Our idea was try to make a game that the play can combine 3 types of bombs (vertical explosion, horizontal explosion and diagonal explosion) to create a lot of different bombs to explode buildings. We find a lot of troubles with programming and we couldn't finish the game. Here are an initial version of the mechanics with the 3 types of bombs without the "mix bombs" mechanics:

Controls 
Mouse Left Button (to select bomb)
Mouse Left Button (to set the selected bomb in a terrain)
Mouse Right Button (to explode the clicked bomb)