The chasm width problem in TRPG design is named after how in GURPS, the rule for how wide chasms the player characters can leap over is min(((2×([yards ran before the jump]+(HT+DX)/4+[Extra Basic Speed]+[Extra Basic Move]))-3), (2×(2×((HT+DX)/4+[Extra Basic Speed]+[Extra Basic Move])-3))) feet, a kind of cumbersome formula derived from point spend decisions the player made at build time, but the rule for how wide chasms the GM can introduce into adventure location is… there is no rule.
I’ve called games with this problem half games in the past.
That’s not a slag on GURPS; many games have the chasm problem. Not all do.
It’s not just about the chasms. It’s about everything. Lock difficulties, enemy strengths and amounts, everything. It’s related to the flagging problem.
I came up the blorb principles as one generic solution for the chasm problem that fits many older games and also solves many other things. It’s not the only way, and it also comes with its own set of drawbacks and problems, but it does work.