Stack shields and do hit and run attacks with the flamethrower. Just spray fire everywhere and kite the mobs through it. Any fire that lands even close to a spawner causes it to pop.

I first started a free play game, wondered why there was no tutorial, wondered why there was no music, derped around trying to figure out how to collect resources, got annoyed how slow collection was (couldn't figure out how to build a pickaxe), wondered why 'I' key didn't open my inventory, couldn'...