This would be a fun game if it could also run on lower spec pcs.
Incorrect. The game IS fun, period. It would be more fun for YOU if YOU upgraded your PC.
Your having an old PC does not make the game less fun. The game is what it is. You just need to upgrade. And hey, if you can't, I understand, I do, but it doesn't make the game any less fun because your computer is slow.
Food for thought.