The VDP's Mode 4 was the secret sauce; it made the SMS graphics almost on-par with the NES. You still have 8x8 tiles, but with a single 16-color palette instead of four different 3-color palettes. For scrolling, the NES has 2-4 screen buffers, but the SMS just lets you hide one single row and column of tiles offscreen. This isn't as bad as it sounds since -- on SMS you can write to VRAM at any time during the frame, as opposed to NES where you can only write during vertical blank.
I've ported a simple NES game written in C to the SMS (https://8bitworkshop.com/projects/?n=sms-sms-libcv/chase) and I think it'd be feasible to write a translation layer between the two platforms. Sound might be a little tricky, since NES's APU is more advanced.
I've ported a simple NES game written in C to the SMS (https://8bitworkshop.com/projects/?n=sms-sms-libcv/chase) and I think it'd be feasible to write a translation layer between the two platforms. Sound might be a little tricky, since NES's APU is more advanced.