fan games are fragile things themselves.....
most either never get completed, and those that do look enough promising are shot down by the original game's company before it can make it
outside.
take Chrono Trigger as an example:
many fangames out there, most either are just very badly done mods or never got completed, and those that do, (Crimson Echoes comes to mind)
are strategically C&D'ed by Square Enix during the last rounds before released,
multiple companies who act against fan-games usually wait for one to be completed before sending a C&D in order to lower developer morale.
ironically enough many fan-devs have developed their own counter-technique.
there was this one fan-game for the game "Streets of Rage" which was very well made, had a supporting developer team + fanbase, and SEGA had it's eye on it,
the devs were about to release their only public (also final) version (5.0) and SEGA came crashing down with the C&D,
however someone, "leaked" the full version one day earlier than the official release, so in response, the dev team DID cancel their release however the game itself
is fully accessible, eventually SEGA stopped caring about the leaks and the devs still have support for the leaked version 5.0 (they even made a v5.0b)
so yeah, fan-games are scarce and fragile indeed, but not all of them are bad, as a rule of thumb, if you find a fan-game drifting out there that's no longer
available because of C&D it might be worth a shot playing as it was probably on it's final stages of completion.