The fact that the game has been seeing continuous development of relatively complex new features for this long means the code can't be too horrible. Perhaps very idiosyncratic and particular to Tarns personal preferences, but certainly not unmaintainable (this is just an assumption though).
I have maintained a fork of LCS. The code is unspeakably horrible. It's like its been run through an obfuscator. It requires a hardened, dedicated developer who has developed life-long immunity to code cooties to hack it.
