One of the challenging issues with in-game explosions - is to decide how you'll deal damage to the player. First, it should be an area damage and regardless of the player's position he should receive damage (if he stays close enough).

If you used tiles in your game, you know what I’m talking about. Usually its white lines, but they can be of any color, and it can drive you crazy. It looks like that the problem is related to how unity allocates tiles from your sprites.

I started experimenting with game development. For now, it's a hobby, we'll see how it will go :)