The biggest problem with my game was that its mechanics weren't entirely clear to players who were playing for the first time, so my goal was to better explain what was happening in the game. This is what I added:

Tutorial

The most important change is adding an explanation in the form of a dialogue before the game starts. It explains the main mechanics and goals of the game. I hope it will help new players understand what to do.

New UI elements

I added popups showing the number of souls and sinners when you get them and a popup informing you about the completion of the quest. Additionally, when the quest is already done or you can buy some upgrade, an exclamation mark is visible in the upper right corner. This shows if the player is making progress without going to the menu too often and interrupting the game.

Additional visual effects

I added camera shakes, a shadow under the player and enemies, and small popups informing how many souls or sinners the player received. I also added custom cursor matching style of the game.

Now my game doesn't feel so bland and is much more enjoyable to play. I hope you will like it :)