Piepacker has Spacegulls as a built in game added by the Morphcat team
They are partnered with each other and also the survive is free with the game
The game runs the same as the emulators

To sign up and play
https://beta.piepacker.com/

Homepage and info
https://piepacker.com/

I don't see why it wouldn't be allowed. Just state that you're using it when submitting a run, please.