How much of a game can be copied or reimagined? Because Backpack Hero itself borrows from Slay the Spire. There are hundreds (thousands) of games that look and play just like Tetris, and many even copied the name of it. Speaking of wich. The tiles used in our very Hero game look suspiciously like all the Tetris blocks for some of the characters.
Having a deck builder not use cards, but space and item shapes, is that forever reserved for Backpack Hero? Is Bph even the first to do this?
That copycat of course copies a bit too much, imho. Even the dungeon view looks like a copy, or the bricks. The events are a bit different, but it might just have been copied from an earlier version.
But once you have the idea of: make slay the spire, but with inventory management, instead of deck management, you pretty much have a clone of backpack hero already.