Hello~ If you're only interested in the artwork from this pack we have options available for that. This package is only intended to be used with GMS and we don't have any support for Unity at this time.
The art only pack can be found here, bundled to more than 50% off: Dokimon Assets Bundle
Viewing post in MonMae + "Retro Boy [COMPLETE]" Bundle Pass comments
Hahahaha, ain't that the truth!! If you're feeling like you need more information, I'd like to suggest watching our MonMae Tutorials to get a feel on how easy/difficult building with MonMae is. In our experience, at least for beginner devs GMS has a significantly easier learning curve. Solo deving is already extremely difficult and time consuming alone, even for the veteran developers. And we believe GMS gives the most power to developers, whilst Unity is better for bigger projects that teams can tackle together.