Birthday party on a budget

My son is turning 8 next weekend and we’ve planned to have his party at our house. He’s invited all his friends as we didn’t want to leave anyone out, but that leaves me having to entertain 20 kids provided they can all come. Fingers crossed not all can make it haha. He also wants his party to be Minecraft theme unfortunately with my maternity leave pay and Christmas coming up I literally have no money. Any idea how to entertain these kids without having to spend $$. We did buy a piñata, what should we fill it with? I found piñata filler but it was like $36 for cheap toys that I highly doubt these kids will be interested in. Also what should I stick in the loot bags? Is it cheap to just fill them with candy? I want to give him the best party ever but my finances of course are getting in the way of that.