Optional (Chapter Select)!
In order to unveil a secret of Solaris, all dots must be blue. If you activate a dot, all other dots in a cross form will also become active. Often you have to throw two projectiles at specific dots, so that all of them are lit up altogether. Only two of such activations remain active, the oldest activation state gets disabled when another projectile is thrown if more than two activations are present.
Often you can reset an artifact's complete activation of dots by using a ground switch nearby.
You can correct gamma setting under options, in order to better distinct the blue lights from the yellow lights.
Deep inside after the Vault before you reach the stone bridge next to a waterfall to the right is this secret at.
You must activate all four grid plates in order from left to right. You have two throw one or two projectiles at each one of them in order to activate them. All dots must be blue to activate a plate. You have to throw your projectiles at two specific dots on each plate, so that all of them are lit up altogether.
After venturing through the village sections, get to the stone picture. Position yourself directly on the left back edge of that stone picture. Then look in the direction that edge is pressing towards. Visualize a lantern in extreme distance. Get to it, and in its nearness, the access point to the relative difficult secret is there at. Keep looking good for the line ups of dots, and also use the switch nearby to rotate one half of that pillar until you have finally unveiled its secret.
In the Administartion room of the ground floor which is past the floating heart, this secret is located at. You must control three switches to rotate plates that have dots on them, but there are also dots on a wall and ceiling. You know what you have to do, and it is only important that all dots are blue alight.
Desert - not to be missed :
After progressing over the rope bridge in the Desert, you will have to open up a gate by first activating a switch one time, and then throwing two projectiles onto yellow dots at the central artifact.