So I’ve played a lot of Game Dev Story as I’m sure many of you have.
I also am aware that some of the ideas I’m about to suggest may have been brought up but to be honest, I don’t have time to read through all the threads 
As well please keep in mind that some of these ideas may have been created in mods but having a more polished version (if possible) part of the game would be great.
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More data/information on a game - after you release it (ex. something as simple as how much the game is going for) and when it is taken off shelves.
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Ability to select publisher/where it gets sold - Maybe later in the game when there is internet, it can be digital like on Steam but instead call it Mist or something clever.
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More Realism -
A. Maybe the dev finds all the bugs he thinks is there but there are still some out in the wild (release can be as good as the best releases or as bad as ACU). So you can release updates, etc to make the game better.
B. Players find exploits or want updates to fix some boring things
C. DLCs - I know there is a mod but the mod is very limited.
D. Mod Support - maybe the game released allows the audience to mod it (i.e. skyrim) and there is a chance or whatever that the community will want to mod it, thus reviving or driving sales, etc
E. Longer shelf-life - I feel, though I can understand why it’s in place, the shelf life of a game is so short. In real life, games as old as Counter-Strike or Diablo 2 are still being played or purchased. I think the game should be out there indefinitely or at least a longer than a few months.
F. Mass Production - Maybe allow for the dev to choose how many copies to make cause each copy made has a production cost (if it’s a physical copy), etc.
G. Development Time - Ability to select how much time you put into the development of the game.
4. Platforms - Ability to select which platform(s) to develop the game on
5. Smart Competitors & Notifications - Maybe somehow incorporate what (local) your other save file games made and have them being fed as notifications every now and then if it’s a big mile stone. For example my first save i made game Y as Company X that broke the record for most sales in a week at 50mil. I play a new game and say around year 5 the game tells me company X sold 50mil of game Y. This can be applied to what other people made too (even if it’s faked or maybe what your friends made/achieved). It would make it feel more alive and it’s not just you dominating the market with people only making consoles.
6. Reviews - This deserves it’s own section. The 4 reviews you get, albeit I’m okay with 4 (wished there were more reviewers), their dialogue is bland and the same. I wish there was more diversity than just “it could have been better”, or, “it’s been done”, or “a great hit!”.
7. Missing Elements - I just realized that the bubbles (bubbling during development) is rather limited. I would like to see more categories (like in Game Dev Story) such as: sound, graphics, fun, gameplay, etc.
The big issue for me right now is the time (not the overall time, though having slower time pass by is good…or longer time). The amount of time it takes to develop a game and how long it stays on the market REALLY bothers me and breaks the immersion a lot. (despite what i named above). 
That’s all I got for now. Still playing (just started like 2hours ago).
Love the game and the community for it!