Is your game provably fair?
Everything is on sight and verifiable.
As for the speed, the random function is the same for everyone, so nobody has any edge.
A small edge have higher level players couse they got +1 every new level.
A level 1 rat has his speed rand(10,31)
A level 2 rat has his speed rand(10,32)
A level 3 rat has his speed rand(10,33)
A level 4 rat has his speed rand(10,34)
A level 5 rat has his speed rand(10,35)
A level 6 rat has his speed rand(10,36)
A level 1 cannot play with a level 6
A level 2 cannot play with a level 7