You offer virtual currency in your game, the currency can be either bought or earned through some game mechanic. If the player takes 1 hour to earn 1 credit. How much do you directly charge them for credits? Does anyone know what the popular freemium games use? Are there any articles on this?
Player here. My time is percious to me. If your game is a credit an hour then that credit better be worth good items. If a credit is the basic currency and rates for items reach into the thousands, I am going to abandon your game. Simple. I am willing to buy IAPs that expand on content, currency no so much. If you create an enviorment where the grind makes my effort seem hopeless, I just won't support it.
Sorry I think my question was confusing, what I"m asking is how many "credits" per hour do freemium games allow you to earn? For example in clash of clans you earn gems, gems cost you 1 cent a piece at $5. When playing at the start you earn gems pretty easily, to get you hooked into the game, but later in the game I assume they are harder to earn. How many gems per hour can you earn?
You're asking the wrong question. Your gem's have no value in and of themselves. The question is how quickly do you want your players to be able to progress given some natural flow of premium currency. For instance, suppose your premium currency allows a player to skip a stage or be able to continue a stage after a death. How often do you want a player to be able to do that. Or if your premium currency buys something cosmetic, how often do you want the player to be able to do that. Your premium currency only has value relative to what they can purchase.
Depends on your own ethics, and the audience you aim for. Lots of games that have massive paywalls (aka "no progress without investing into IAP) also make massive profits. But those aim mostly at casual gamers, from what I have seen. If you are in a niche, check your audience very carefully: e.g. (oldschool) RPG (real roleplaying games; think e.g. Baldur's Gate, not what passes as RPGs these days) gamers like me are easily turned off by hitting a paywall, when resources earnable in game do not correspond well to the amount you need to make progress. Like saansilt said: If the ratio isn't right, and I hit a paywall or feel that you want to milk for cash, I put your game in the trashbin.