Tower Locked by Miroslaw Zielinski Free

  

Tower Locked comes from Miroslaw Zielinski.  It's a math puzzle. The objective: delete some of the red circles so that numbers left in each row add up to the number matched on the sides.  Same with the columns.

I have no idea how many levels there are. But the grids go from 4x4 to at least 8x8. That's at level 8, which I did not solve.

The small grids are too easy. The perfect grids are 6x6 and 7x7.  But there's no way to select just those.
https://itunes.apple.com/kr/app/tower-locked/id1173339247?mt=8