Rather than add, I think you should make sure everything you added so far works really well. (I’m assuming you added the minigames thing so it seems your core game is done) An easy way to do this is to do a soft launch to make sure everything is good before you pour a tonna $$$ into an actual ad wave.
Again, I’m no expert on the subject, but I will give examples.
Supercell’s clash of clans did well despite entering a crowded market because they had employees test the game for hundreds of hours. The game was proven fun before it was released.
The same can be said for Treelands, a more relevant example as it’s a roblox game. From what I’ve heard the game was tested for a month before release. And since Fissy worked on both Treelands and Adopt Me, I’m assuming the same was done for Adopt Me, which is the most successful roblox game as we speak.
Obviously, you don’t need to go to these lengths to succeed. But the benefits of a good, thorough soft launch are real and you should definitely keep it in mind.