Readability and permissiveness

I read that gamers spend more hours watching others play than playing videogames on their own.

This inevitably leads to the creation of games that are more fun to show to others. Games that are too complicated to understand or with many fail conditions are penalized. Games are designed not only for players but also for streamers, which are an important driver of sales.

A streamer wants to entertain but also show that he is good. Spending two hours thinking or losing miserably because you made bad strategic choices at the beginning is not the best. This is probably why puzzle games are not so popular on Steam. This is also why RTS games are not trendy anymore, probably.

Streamability depends not just on the genre, but on two factors:

1. the readability of the mechanics, having something that can be understood from a 5-second video is key
2. the permissiveness of the rules, the black box is better if it allows epic wins even at the last moment.