Played for around 20 minutes, and the entire time my CPU fans are just going full RPM.

Seems extremely excessive with this kind of game, and very distracting with the noise. I don't even get that kind of noise when playing something like Cyberpunk 2077.

I have a 9700k and when I looked at task manager CPU monitor it's running at 4.8 GHz with CPU ulitilization anywhere from 25 - 50%.

Me over here too. I have a 5700x with an noctua nh15 am4 and the fans are roaring.
Sorry, this has to be fixed...

Edit:
Found a fix or kind of a fix: You have do download the current solarus engine for your operating system, for win10 64 bit it was solarus-player-x64-v1.6.5.zip from https://www.solarus-games.org/download/, in this zip there is a folder "solarus", copy all files from it over to your game folder where you can find oceans-heart.exe. Overwrite any files if asked and then start the solarus-launcher.exe.
Here you have to add oceans heart via the button "add quest", the file which you need is the "data.solarus" from the game folder.

Now you can start and play your game with said solarus-launcher and without overcooking your cpu and electric bill.
Do not use the oceans-heart.exe!

TO THE DEV: PLEASE UPDATE YOUR EXE WITH THE NEW SOLARUS ENGINE FILES!