Socializing an adult male feral

We have a 4 year old male feral cat living in our spare room for 4 months. It's been slow going, but I managed to get him neutered and dewormed 2 weeks ago. When I put his food down he rubs his body against my arm and I've patted his back. Lately when I try and leave the room after putting his food down, he leaves his dish and darts at my leg and punches it. His claws are slightly out, and his posture is low to the ground. I've tried sitting down and trying to play with some cat toys, but he stares at me and punches me. What does he want? It kind of scares me, but I try not to show it. I've got him responding positively to me bringing the food in, but where do we go from here?

My guess is he tries to provoke wrestling play with you!  When they are playing with each other, different wrestling games are the common. 

He probably wasnt very dominat male, so his hormone level is already visibly falling down.  And thus - he is playful again...       

This with the punches (a lightly blow  with the paw, yes) is a recent development, AFTER his neutering, yes?

It should go easier and easier now, now when he is neutered.

Alternative mode for slapping with paw (usually soft paw) is to teach lessons, but it doesnt seems to be so here.

Good luck!

Yes! It is a development after he got neutered. I think you're right, I think he's trying to play and its the only way he knows how. But I don't want to hand wrestle him, and he doesn't seem to be interested in any commercial cat toys. Any ideas on how to redirect his play?
Also, yesterday I was pretty frustrated with this whole project. Then this morning, he purred! It just bubbled out of him like he couldn't stop. And he let me scratch the top of his head. Every time I'm ready to give up, he gives me a sign.

Smart not to hand play with him.  They always win those!

Kong makes a great stuffed rectangle that has a tail and is scented with catnip.  My cats especially love to "rabbit kick" it.  I can drag it across the room and they like to attack the tail.

There's also a wand toy that has a long length of fleece attached instead of a feather.  You can make it wriggle, which drives them crazy.

What about a laser pointer?

The two times I gave him catnip, he literally wet himself. He peed on the scratching post and the second time in the middle of the bed! So that's out. I like the wand with the fleece on it idea, I don't want to wave a stick at him, but you're right, I can wiggle it. Also, I feel dumb not having thought of the laser pointer! We have several around the house. Side note, yesterday I caught him a grasshopper and let me tell you, that was a huge hit! Thanks so much for your suggestions, I will try both tonight.