Regarding the laggy nature, I think anyone who has worked with minetest long enough would realize this is the norm especially with dealing with entities of this scale.
Putting that aside, this game does introduces some pretty impressive mechanics. The fact that the AI cart players (for most parts) actually work is impressive enough for me to provide a thumbs up.
The gameplay is fun and has a lot of interesting powerups, karts while laggy, are still very responsive to controls.
Even in endless singleplayer its definitely fun enough for me to play continuously.
I definitely look forward to more stages & multiplayer being released.