There are plenty of competing engines, like
- [Trisquel-users] MonoGame - is it free software ? mjmhogg
- Re: [Trisquel-users] MonoGame - is it free software ? dhood
- Re: [Trisquel-users] MonoGame - is it free software ? t8mf4nu6lizp
- [Trisquel-users] Re : MonoGame - is it free software ? calinou
