Kudo for anyone unfamiliar, is a mixed martial art founded by Azuma Takashi, an accomplished Kyokushin Karate fighter, who found that Kyokushin had become too watered down from the original Oyama style of karate that he had begun his training in. Similar to Ashihara karate, this offshoot of karate was founded within the lifetime of Mas Oyama, the founder of Kyokushin and was decidedly made to be a comprehensive martial art. Kudo involves all aspects of striking, as well as the throws and takedowns of Judo and BJJ. In where the martial art becomes weak is in it's ground fighting. There is only ten seconds of ground fighting allowed in Kudo, similar to Judo rules, where the ground time is limited and only becomes extended when you have a pin.
I believe that Kudo offers an interesting alternative to MMA. The two arts are extremely similar, however Kudo has three elements that differentiate it from MMA. The first as already mentioned, is the shortness of the newaza or ground fighting. The second is that Kudo is fought in the gi, which allows for stronger grips and different takedowns that would not be available in MMA or no-gi. I find the gi adds a lot of realism to Kudo. In the northeast United States where I am, people wear jackets the 3/4th of the year, and being able to use that to your advantage in self defense situations gives Kudo an edge in my opinion. Thirdly, and perhaps most importantly, is the headgear. Kudo uses a large headgear with a plastic face plate, if you're familiar with Bogu karate, then you'll recognize the similar style. The main ideology behind this headgear is for safety and to allow regular people with office jobs, to train Kudo and not go to work with black eyes, and bruises. However the headgear allows for an interesting facet of Kudo, headbutts. You can use the headgear to headbutt your opponent in the clinch or at the end of a combination. Which adds another weapon to either use or be wary of. In my first few sessions of Kudo, it was incredibly jarring to get headbutt in the clinch, not only did the headgear make an audible clashing sound, it simply wasn't a position I expected to be taking damage in.
Here's some Kudo Dojos and Practitioners I'm a fan of: