There isn't a starter kit and I don't believe anyone has developed their own bot in C yet either. So while it probably hasn't been tested the server should be able to handle a C bot fine. You just need to send a
MyBot.c file along with having all of your
.c files living in the same directory. Then if I'm reading the code correctly, the server will compile each
.c file with
gcc -O3 -funroll-loops -c and then the overall bot with
gcc -O2 -lm -o MyBot <all the .o files>.