Correct me if I'm wrong, but it sounds like you're describing Facebook Portal. Source: about 3 years ago

For those who don't know what it is here is a link to their page: Https://portal.facebook.com/. Source: about 3 years ago

If you're looking for a good spin-off, mari0[0] is a really fantastic Super Mario Brothers-meets-Portal game. I just wish development had continued and provided more levels. [0] https://stabyourself.net/mari0/. - Source: Hacker News / 9 months ago

If you're cool with 8-bit Mario, there's a Mario fangame called mari0 that gives Mario a portal gun. Source: about 1 year ago

There's a Mario fangame called mari0 that gives Mario a portal gun and allows up to 4 player hotseat multiplayer. Source: about 1 year ago

Mari0, the Portal/Super Mario Bros crossover was made with Löve2D so yes, it definitely can as any other framework/engine. Source: over 1 year ago

Lol. But in seriousness finding time and motivation to play everything I've downloaded would be wonderful. Unfortunately time is limited. I still seek to preserve what I can. My favorite mario fan game has always been and always will be Mari0, a Mario + Portal crossover which has remained free to access for 10+ years at https://stabyourself.net/mari0/. It could be because of nostalgia though. Super Mario... Source: over 1 year ago