The short answer is that I -don't- look for animal sim games. I've played a few that were good, but the majority I've played turned out very badly.
The longer answer is that I look for the same thing I look for in any CYS: choices, good grammar, good spelling, good plot, engaging characters, and entertaining dialog. For a dragon sim in particular, I'd recommend that you read "Choice of the Dragon" which is not a game here, but is popular among people who like animal sims and CYOAs. I like it, myself.
I'd also like to strongly recommend not plagiarizing, just learning from it. It's a flawed game, mind you. I've played it several times and I always get the same ending which I would normally find really annoying (and I suggest you make multiple endings...)
But it allowed multiple styles of play to get to that ending: You could be a tyrant beast or a noble reptile, you could eat your goblin minions or grant them mercy, you could kidnap either gender of royalty, you could kill a sorcerer, spare and ignore him, partner with him to kill another sorcerer, so on.
You also had your pick of mate, each of which apparently responded to you depending on your past and current actions, and could individually be impressed by your fierce reputation, or your wealth, or your cunning, or your skill in flight, and so on. Every action you made could potentially increase your wealth, your injuries, your ferocity, your infamy, exc. What was also nice was the ability to keep track of those traits and see your scores in them whenever you wanted.
There were also little cosmetic choices like: 'are your wings leathery or scaly', 'do you have two, four, or six?' 'Is your head smooth or ridged,' 'what color are you,' 'horns, no horns, antlers, spikes' and so on.
I think readers would be pleased, even impressed, if you studied up on types of dragons and gave us a truly wide range of choices on what kind we can be. You may not realize this, but there are -several- different kinds. The European portrayal that so many people are accustomed to is barely even scratching the surface.