TLDR: More than 12,000 games are coming to Steam every year now. I suggest it's good for gamers, bad for small or solo developers, but how this impacts AAA studios is uncertain.
What is the impact of more than 12,000 games coming to Steam every year?
Gamers (Especially niche gamers)
For gamers, especially niche gamers, this is almost too good to be true. Every type of game imaginable is having new entries coming out all the time. This wasn't true just a few years ago. I, for instance, like retail economy games, and so far this year we've had several good ones with several more on the way. Even getting very specific, like movie studio or hospital management games, shows a good number of entries.
For instance, here are the movie studio games that have either just released or are releasing soon (in the next few months):
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The entire management/economy/tycoon game genre is booming, from taverns, to hotels, to blacksmiths--you name it, they are here in droves.
And it's not just these more niche games. Pretty much every type of game is represented.
The Industry
On the one hand, it's great that anyone can make and sell a game these days, but it has to be tougher than ever on small or solo devs. There are just too many games for most of them to get noticed.
AAA studios don't seem to be impacted as much. The top 100 games on Steam account for 90 percent of the sales revenue. That remaining 10 percent is still a large pool of money for smaller devs to compete for, but if a AAA studio finds itself in that group, it's bad news. Could the average gamer, who used to only play AAA games, be branching out into indie games? Could this flood of games be partially responsible for the volatility in the AAA space these days?
What is the impact of more than 12,000 games coming to Steam every year?
Gamers (Especially niche gamers)
For gamers, especially niche gamers, this is almost too good to be true. Every type of game imaginable is having new entries coming out all the time. This wasn't true just a few years ago. I, for instance, like retail economy games, and so far this year we've had several good ones with several more on the way. Even getting very specific, like movie studio or hospital management games, shows a good number of entries.
For instance, here are the movie studio games that have either just released or are releasing soon (in the next few months):

Blockbuster Inc. on Steam
Ever dreamed of making your own movies? Build up your own movie studio, scout for upcoming stars, and produce cutting-edge films and TV shows. Try to stay ahead of your competition throughout the history of cinematography.

Movies Tycoon on Steam
Movies Tycoon is a simulation game where you dive into the world of film-making. Start with a humble studio, scout and manage top talent, customize unique characters, and direct blockbuster films.

Hollywood Animal on Steam
Make your dreams come true — or crush someone else’s. Take the helm of a major Hollywood studio at the dawn of sound cinema, and guide it through decades of creative achievements and glamor, debauchery and dark deeds, tough choices and unpleasant compromises.

The Executive - A Movie Industry Tycoon on Steam
Shape the history of the Hollywood movie industry in this sandbox business simulation game. Create the movies you've always wanted to see, hire the best team, research cutting-edge technologies, and dominate the Box Office. Can you rise from a small studio to a Hollywood giant?
The entire management/economy/tycoon game genre is booming, from taverns, to hotels, to blacksmiths--you name it, they are here in droves.
And it's not just these more niche games. Pretty much every type of game is represented.
The Industry
On the one hand, it's great that anyone can make and sell a game these days, but it has to be tougher than ever on small or solo devs. There are just too many games for most of them to get noticed.
AAA studios don't seem to be impacted as much. The top 100 games on Steam account for 90 percent of the sales revenue. That remaining 10 percent is still a large pool of money for smaller devs to compete for, but if a AAA studio finds itself in that group, it's bad news. Could the average gamer, who used to only play AAA games, be branching out into indie games? Could this flood of games be partially responsible for the volatility in the AAA space these days?