Needs to be things to keep me engaged. At least a goal to work towards, even if the actual activity of playing the game is simple and repetitive. The in-game mechanics need to be polished and fair, not gimmicky with high fail rates. I should not be punished for playing on a pet site, that makes me want to quit. Lioden, with its massive amount of engaging activities and different ways to play the game was by far the best pet site I've ever played.

Obviously I join sites about things that interest me, always about animals/creatures solely. I don't like making a human avatar, but Pokefarm Q I'll excuse (because it's Pokemon.) As I mentioned before, mechanics designed to punish you or are incredibly unfair are a no-go. I will not play your game.

Premium currency should be obtainable as Flight Rising and Lioden do it--as in, you're allowed to sell your items on player market boards for said premium currency. It's still hard to make, but not completely barred off from people who cannot pay for it. "Exclusive shops" for paying members only containing necessary or important items are the worst. There should be a way for all players to make a little bit of that money.