Super Robot Taisen BX is a tactical role-playing game developed by Bandai Namco and published exclusively in Japan for the Nintendo 3DS in 2015. As part of the long-running Super Robot Wars series, BX brings together mecha from various anime franchises in a crossover tactical RPG. The "Rev 1" refers to a later cartridge revision containing minor bug fixes and adjustments.
The only legal method to own the game is to purchase a physical Japanese 3DS cartridge. You can find used copies on eBay, Amazon Japan, or Play-Asia. However, to play it on non-Japanese hardware, you need: Download Super Robot Taisen BX -Japan- -Rev 1-