Clearing huge tons of enemies is satisfying

• Doing it in different ways is necessary for replayability

• Relics/Items synergies are essential for nailing the increasing power fantasy

• References games are Vampire Survivors and 20 Minutes Till Dawn

Ascyrohous Multiplayer done well is great for mobile and you don't have to deal with connection issues; Super Auto Pets

Mobile Game Icons with portrait seem to work the best

Variability in gameplay:

• Making locations affect gameplay e.g Marvel Snap

• Make sure no gameplay looks the same when you play again

• Randomness is your friend

Stunning Character designs with new themes are easily marketable

Add pacing and different kinds of interactions to break up gameplay helps with the retention

Juice and effects are very important to make the player feel good

Adding a way to enable community growth is essential for long-term growth:

• One idea I want to try is the community sharing their creations in-game

Having idle mechanics within your game boosts retention

Voice-acted feedback adds to the experience; Marvel Snap and Candy Crush

Story is a nice way to add depth and intrigue to your world and give your players emotions to feel

Make winning feel great, celebrating them hard and making losing feel awful

The best game mechanics are puzzle games and the best puzzle games are problem-solving games

Check out the list of top games this year:
https://www.reddit.com/r/Android/comments/zrja3w/after_covering_100s_of_mobile_games_this_year_on/