In-game currency. At the beginning of the game, the player starts with a reactor that allows hea ng the reac on up to 573 K and two chemicals H2(g) and O2(g). In addi on to chemicals, which will be unlocked upon comple on of specific levels (this is predefined in the game script), at any me, the player may exchange the gained points for chemicals with posi ve enthalpy of forma on (Table ). The player may also exchange the gained points for reactors that allow hea ng the reac on up to 1773 K and 3273 K, respec vely, and light emi ng diodes (LEDs). Figure shows the interface of the game shop. A er any of these virtual items are "purchased" they remain available for player in all the subsequent levels. Upon purchase of any item, specified in the "price tag" number of points will be subtracted from player's total score (see Figure ). As inferred from Eq. 1 and 2, using chemicals with posi ve enthalpy of forma on as reactants lowers ∆H 0 and, as a result, decreases ∆G. On the other hand, LEDs may be used to generate electronically excited state of reactants. Such species have less nega ve (or posi ve) ΔHf 0 compared to that of the ground state. Schema cally, these differences in energies are shown in Figure .