I just read through the SRD and my rolegears have been turning since. I have just one question, though: did I just miss it, or there aren't any references to how many points attributes should have? I get that it might depend on the game one's running, and it can be inferred by similar games to get an idea of the ranges, but at least a broadly defined reference would be really helpful.

Apart from that, I love how speed is addressed and stressed throughout the SRD, and the overall coherence of the rules and dynamics is great. The videogame feel is also strong, I think I could already run a few vg inspired games with barely no prep.

The seeds for an illuminated metroidvania kind of game are slowly taking root in my brain.

Hi! Glad to hear you're digging the SRD so far. As a rule of thumb that I use in my games so far, a point buy of 4 points during character creation is used for the Attributes. Every Attribute starts at 1, and then players can increase the Attributes however they want by spending 4 more points on them. Advancement lets them boost those up one more time in LIGHT, for example. Hope that helps!

Love the idea of a metroidvania game using LUMEN!

This might be something to add to the next iteration of the SRD; not everyone who reads it may have purchased or read LIGHT.  They may look at the SRD as a quickstart product to see if they like the system before making a purchase.