I just finished Interspeller, and I'm thrilled with the gameplay and level design quality. The way you taught how to use spells to the right and to the left right at the beginning was awesome, and showing indirectly instead of "saying X put enemies to sleep" makes the experience of discovering spells more rewarding. Excellent game!
But you REALLY need to do something about the fonts, mainly those of the portals. They are buggy, and when I was using the teleport spell I couldn't teleport to some places because the names were bugged and I was misreading them (like foa instead of foo). I noticed the main problem is between "o", "a" and "c". I had to restart the game to get rid of the bug (though I never found out the real name of one of the portals).
When you fix it, it will be an excelent game! Congrats!