Got the game.
I checked for PSI energy at the starting level only.
I found that, at module address 1A0540, for me 005A0540, the game sets the full values as follows
005A0538 - mov eax,3f800000 //default value
005A053D - push ff
005A053F - push esi
005A0540 - mov [esi + 20],eax //reference value
005A0543 - mov [esi + 18],eax //PSI energy value 1
005A0546 - mov [esi + 24],eax //PSI energy value 2
Then, at module address 9FA0D, for me 0059FA0D, the game decreases the energy.
EDIT: I discovered later that the following decrease it when using Telekinesis.
0059FA0D - fld dword ptr [00901478] //get something
0059FA13 - fmul dword ptr [00794380] //multiply once, floating mode
0059FA19 - fmul dword ptr [0071ca6c] //multiply again, floating mode
0059FA1F - fsubr dword ptr [ebp+18] //subtract from stored value and keep in FPU
0059FA22 - xor edi,edi
0059FA24 - fstp dword ptr [ebp+18] //store decreased floating value and pops
0059FA27 - mov eax,[esi+000000dc] //next opcode, 6 bytes lenght
EDIT: Going further in the game, the memory addresses where it stores the values change.
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SPECIAL QUESTION: how do you discover these nice games ?