Check game subscription value by playtime.
A game subscription pays off on two different tests. The purchase-replacement test asks whether the games you actually played would have cost more than the fee, which depends entirely on counting games you played rather than games you added to a list. The engagement test is cost per hour, which is how a subscription compares against any other entertainment spend and is where a single long game can justify a year of fees.
Purchase replacement
Saving = games played x price if bought - monthly subscription cost
Engagement value
Cost per hour = monthly cost / hours played; break-even games = monthly cost / price per game
Not at full price. The honest input is what you would actually have paid, which for a curiosity you tried for an hour is often nothing.
That is the hidden cost. A title you are halfway through can rotate out, and finishing it then means buying it anyway — worth factoring in for long games.