I'm pretty sure reaching this switch is impossible, because the gap between these rocks is nonexistent, and isn't allowing my character to walk through without an upgraded sword.
Hi, yeah you are right, it is impossible to reach this switch with the sword.
You have to get the firestaff first (which is located in the same summer/sand dungeon) and use the firestaff (with right mouse button) to shoot a fireball to activate the switch.
Better solution would have been to use a different hurdle maybe a hole so that the player understands better that this switch can`t be reached on the normal way.
In the end we had not enough time to polish a lot of elements of the game. And this is sadly one of those areas.
We would love if you give it another try after this "tip"
Thanks for your feedback!