An aligator lying in ambush at water's edge will charge an aproaching game animal. The Florida Natives would use a big log sharpened at one end, charge the gator, who would counter-charge and get a log rammed down his throat for it.
I've never tried this one.
You can kill many critters with a knife, but you have to be able to close with them. Stalking is a tricky skill to learn, I reccomend COl. Applegate's Scouting and Patroling plus a lot of practical experiment on stray cats(stalking, not killing). When you can get close to an alley cat, you can get close to anything.
Anyway, get close, then sprint at your game. The way we take down boar these days is to pounce on them from behind(preferably), sweep their legs out from under them with your own while wrapping your left arm around their neck and grabbing their right leg and pulling up so as to pin the head and expose the armpit. Shove a long blade up inside the soft armpit and wiggle.
You usualy won't get hurt after you've perfected this, but learn'n's a bitch...
Maybe you can practice on a buddy, without actualy sticking the knife inside him. Just don't let anyone see you jump on top of your friend who's down on all fours and then intertwine your legs and roll around. They might get the wrong impression...
Racoon, possum(remove the musk galnds and they are palatable), armadillo can all be clubbed if you get close enough.
The key is to be willing to play them for a real long time. Freeze when ever they look up, aproach when they look away or are eating something. Never try to get too close to fast, and know how to play tree.
They aren't smart enough to figure out why you're getting closer and closer, but they are smart enough to detect all but the most subtle approach.