Sure thing! GTA 5 average game time was 52h (main+extras), so its price is then about $1 per hour at launch. Looking at my Steam library, I’d probably have saved hundreds if not thousands over the last 20 years if all the games were billed like this…
Have fun implementing the payment system that reliably measures and bills this with zero downtime, internationally! And even more fun when nobody mysteriously chooses to subscribe to this shit.