The big issue isn't engineering, it's licensing. In the words of the attorney that helped me with a Nevada gaming license application, "They really want to make sure you're clean before they give you a license to steal". For example, if you went to high school in Hawaii, they will send two gaming agents to Hawaii - on your dime - to interview your high school teachers. The process is long and expensive.
And that's just Nevada. You have to be licensed in each individual jurisdiction where your games will be shipped. This, of course, is all before you even broach the subject of putting your game on casino floors with slot/table game managers.
As far as revenue models, both of those you mentioned are used. This also goes back to licensing - if you are only licensed as a manufacturer (a slightly less onerous process) then you cannot get a percentage of profits. You must have an operating license to obtain a percentage. This is why many table game manufacturers (3 Card Poker etc) get a flat fee per table per day instead of a percentage. The machine market is dominated by IGT and WMS, and good luck penetrating it. You may, however, be able to develop a fun game and license it to one of the big slot firms. Probably the easiest way.
If you hang out at the back of the Global Gaming Expo (aka G2E), there are dozens of inventors in little booths trying to show off their new game and get you to try it. If you don't have a connection to a big company, this is one way to get discovered, but by judging what I've seen in some of those booths, you really have to have a compelling, easy, addicting game to get noticed. And most of those little guys have none of the above.
Anyone can demo any game they have developed, but before those games go into a casino, they must go through everything I said above. Many of those guys go to G2E to either get noticed by a larger manufacturer, or to find investors to help them go through the licensing process (or convince existing investors to do the same after a good response at the show).
And that's just Nevada. You have to be licensed in each individual jurisdiction where your games will be shipped. This, of course, is all before you even broach the subject of putting your game on casino floors with slot/table game managers.
As far as revenue models, both of those you mentioned are used. This also goes back to licensing - if you are only licensed as a manufacturer (a slightly less onerous process) then you cannot get a percentage of profits. You must have an operating license to obtain a percentage. This is why many table game manufacturers (3 Card Poker etc) get a flat fee per table per day instead of a percentage. The machine market is dominated by IGT and WMS, and good luck penetrating it. You may, however, be able to develop a fun game and license it to one of the big slot firms. Probably the easiest way.