Nice game!
I like this Ollie and Calli "collab" game.
Some improvement suggestions:
1) Have a par marker per hole, as a reference for the player to plan their game strategy.
2) It's not easy to see which way Calli is aiming. I suggest adding an arrow extending from Ollie's head and pointing to the direction the shot will go to help with aiming.
3) It's difficult to calculate shot strength. I found myself wanting to hit just a bit below max power but it was always too low or max power. A power gauge UI on one of the screen edges would help a ton.
4) For short shots, it would help to have a "putter" golf club with lower power but more precise control. Maybe have a button on the screen to change into putter mode.
5) Not relevant to the game itself, but the web page color hurts my eyes. It's not comfortable to look at for long periods of time, so it detracts from the gaming experience.
Due to the difficulty to aim and calculate shot strength, some holes (specifically the "island" ones) become very frustrating and lower the "fun" factor for me.
I still had fun playing and tried playing a second time once I had a better feel for the shots direction and strength.Good game! :)