We simply do a side by side comparison of the original game while developing SMC, so we manually tinker with numbers until it looks as close to the original as possible.
There may be more power-ups in the future, yes! Although they'll likely come after the V8 update.
We're glad to hear you like SMBR as well! They're made by a different team that is partnered with us, and we're open to accepting more games as well.
Not sure yet if we'll get any more 'in-house' games (SMC & YFS are made by us directly), since we're quite occupied with those already! Currently our internal development has a large focus on SMC.
Heya! There aren't any plans to add more styles in the foreseeable future, however, if a third style is to be added it'll highly likely be based on SMAS SMB3.
Regarding the NES SMB1 style, its graphics were actually just changed to SMAS SMB1 art since it's easier (and more fun!) to work with for our artist team - so it technically still exists, just under another coat of paint!
There is a very roundabout way by using spawners using their limit property. You'll need to put one somewhere offscreen, ensure it's loaded and have it detected within your arena for its limit. once the enemy is killed, the spawner will be below its limit and spawn a new enemy, which you can use to trigger a contraption. (eg. goomba steps on noteblock, dispenses shell, hits switch, key drops from sky).
it's currently not on the list of things that could make it in the short term or long term as far as our plans go. This could of course always change depending on what features the site might offer to support this and/or how the priorities of the team may change.
