There are several reasons, why games are so successful on Steem and now Hive - most of them are well known, but I think that two - which are maybe not so well known - stick out:

1. There is an awesome community, which strongly believes in the success of the blockchain. If you come up with something new, you will most likely get a lot of people trying it out or even supporting you with own posts or even own tools which they program.

2. You can just start and build something. No bank account, no nothing involved. Just bring it out into the wild and get it tested.

When we developed Nextcolony, it was awesome to see how people were supporting the project. And when I announced that I am working on a new soccer manager game a few weeks ago, there were immediately some people offering to help, partner up or do whatever together. This is extremely helpful in getting something started!