While installing it (see attached pic). Yeah. Doesn't seem fishy in the slightest.
The music... Not very good quality imo. But I guess it's okay for a fan game.
I played it with the keyboard, only got through a few stages, but I suck using the keyboard for scrolling platform games.
ETA: ...It's probably not worth the trouble. The controls feel a bit different from the SNES Mario games (like jumping higher), also the enemy collisions seem different somehow... I think it's that they keep moving - whereas in the official games they stop. It does have a level editor (haven't tried it yet), and I suppose if you're looking for different stage layouts - then it might be worth a go.
I wasn't able to set the controls... That's why I used the keyboard. You can choose the control pad with the keyboard, then after that you can only do things with the mouse... Then you can't do anything else... except close it.
I'll run a scan later to see if I'm infected with anything.