I like to make Italian (sweet and hot), Chorizo (spanish style), bratwurst, knockwurst, kielbasa (which is really just Polish for sausage, so there's infinite varieties of this one), and the list goes on and on. I started out with Rytek Kutas' book called "Great Sausage Recipes and Meat Curing", which has a ton of good ones, as well as
meatsandsausages.com is a great site affiliated with Stan Marianski (who is a master of all things sausage, curing, etc. in the Polish style....he has a great book, too.) If you like a hot Texas style sausage, Dustin Dorsey has posted his version here. There are really a million ways you could go. Give us an idea on what your top 3 favorite links are, and I'm sure we can help point you to good recipe sources.
I've never made game sausages, so I'm not too much help there, other than I know that you need to add some sort of fat (usually pork) to bring it up to the right level for a juicy product.
One recommendation, when making a new recipe, make a small batch so you can be sure it's to your liking before making 5-10 lbs of it. Also, ALWAYS fry a small test patty of your mix before stuffing......you can adjust seasoning at this point if needed.
For staters, here's what I use for a sweet (ie: not hot.....it's not actually sweet) Italian:
Salt 1.8%
Black Pepper .2%
Sugar .2%
Fennel Seed .3%
Coriander (ground) .1%
Ice Water 9%
The percentages are all of the meat/fat quantity. For Italian, I'd use all pork, and aim for 30% fat. Weigh out your meat, then multiply that number by the percentages above to get your spice amounts. I use grams for better accuracy with small numbers......and it helps to have a scale that can weigh out small amounts (I have a small one I got off Amazon for cheap.)