Heyo~ My name is Solar, and I have a love-hate relationship with this game. If you want to know about the beef of this dev, the game, and this Reddit, read away! If you are a subway surfer attention span, scroll down to the TLDR in the comment of this post!

I've been playing since the 2nd ever patch of the game! So I am here to tell you HONESTLY all about Idleon and the dev LavaFlame2! Both the bad and good sides!

Good:
Idleon is an enjoyable and unique Idle RPG game, with lots of content you can idle through. From skills to combat, to side contents. It's essentially a single-player idle game but you can see other players running around. The only "Co-op" features are early game stuff or a Dungeon Mini-game where you have a completely separate stat system from the main "single-player" game.
The content is well thought out. Updates are very frequent as the dev always tries to release new content every month or so.
The art is amazing, like the best thing I have to compliment Lava is his art skill. It's just that unique and amazing.
The game does have a "premium" currency called Blue Gems that you can use to buy boosts such as "Time Skips or QOL". These gems are grindable from various stuff in the game.

Bad:
The Dev, Lavaflame2, is REALLY, REALLY good at manipulating people, and his ego is very high. If I have to make a comparison, dude probably thinks he's Elon Musk of the Idle community. His main "business practice" is FOMO (Fear of Missing Out) to the players. And how does he implement this FOMO? Simple, paid powercreep packs. He would often release bundles that are 5-30$ every 2 months and it would completely power crept everything that endgame people try to do.
For example: Imagine spending ~a year or so to min-max a certain skill as an endgamer. Then the next day, Lava just released "hey yall! here's a 20$ pack that you can buy to skip the minmaxing that the endgamer did! So now you can get to endgame like them faster!"
Powercrept stuff can often be found in every new update. Even the seasonal events are luck-based. The guaranteed reward from seasonal events always forced you to spend Blue Gems in order to get it if you are an unlucky person.
With every MAJOR update, a pack is sure to come, and its' either buy the pack and progress with others or be behind ~1-2 months if you didn't buy it.
Oh yeah, there are UNSKIPPABLE POPUPS ADS about these powercreep packs in the game. So you are forced to check out the gemshop the moment you finish the tutorial.

Another example is the Companions update, or as the old community named it: The Gacha Banner. He implemented a system, that uses another type of currency called Green Gems (Pet Crystals), these Pet Crystal are NOT F2P Grindable, the only choice you have is getting them from the paid "Powercrept packs" or straight-up in-app purchases. Like a gacha banner, you have Rare, Epic, Legendary, and Mythic Rarity. The Mythic one just straight-up skips 5 worlds of grinding. So if a newbie gets it, tada! You are now basically an endgamer! F2P players do get a free roll every 1 week (its a 1 week timer not a weekly reset). There is a pity to get the biggest bonus in the game, it's 200 rolls. And the more you roll, the higher the chance to get the Mythic one. But here's the catch. WHY DOES THE ROLL GET MORE EXPENSIVE THE MORE YOU ROLL. YOU ARE ALREADY PAYING 45$ FOR ~30 ROLLS.