Thank you! I'm currently using Unity. This is how I did most of the visuals:
- PSXEffects (free alternatives are available) for the camera which let me set render resolution to 320x240 and add dithering.
- I used the PSX shader that came with PSXEffects on some geometry, mostly small props on the inside and the cliffs on the outside.
- Textures are 128x128 with no filtering.
- Models are all very low poly with 256x256 textures.