Everything checks out, welcome to releases! I think some of the tracks would honestly benefit if they were a little bit more wider because some of these turns are super tight. Especially the one right off the jump in Temple of Zoom. Could be a skill issue on my end but those tight hallways could present some issues with multiple racers knowing Kart's physics when you bump into other people.
I disagree it being a skill issue on your end, with how tight the track gets in Temple of Zoom and Artica Snow Base its impossible to avoid well placed mines without going off the track. Road Widths are usually 768 to 1024 fracunits wide which should give players enough space to avoid mines and not have too much trouble taking turns (EDIT: especially for heavyweights) without making the track feel boring.
Temple of Zoom: In the GIF above and below this the dark part of the road is offroad, I am not sure if this is unintentional or not but its one of the places where a mine is impossible to avoid.
Artica Snow Base: There is a segment where the track is slightly hard to figure out where the road and offroad is from the darkness of it, this is followed up by a turn that is impossible to see coming unless you know beforehand. I do like the 3 way split at the start though, its neat!
Arcturus Asteroid: There seems to be no offroad in this map even where you would expect there to be. The item set leading up to this part in the GIF is obstructing a turn so I recommend pulling it back away from the turns
Central City: The boost pads should be the 128 x 128 ones instead of the 64 x 64 ones. in the green water area its really hard to make out the boost pads in the water on top on not being able to get on the sidewalk. The ramp sector (double step up/down) effect might work but apparently it ignores items like orbis.
I would also recommend changing areas with 255 brightness to 224 brightness to increase wall contrast. it also seems like Central City and Arcturus Asteroid have misaligned minimaps.
Overall, a good start, just needs some refinement and some fixes.
