Session-Length restriction

The thing is, however, that whether we like it or not, session length restriction has become an essential characteristic of mobile games and this trend doesn’t show any signs of weakening. So the question is, how should you take it into account when designing your next free-to-play title?

1. You should implement it – even if you hate it

(without energy mechanics, some games would become boring and run out of content very fast)

2. Know which restriction method suits your game the best

a. Energy

This method is often seen in successful RPG’s, CCG’s and match 3 puzzle games with some level of character development.

b. Lives

Many casual match 3 puzzlers use this method.

c. Wait-to-finish

Building focused strategy and tapping games are typical representatives of this restriction method

3. Don’t overdo it!

An average player should be able to have at least 10 minute gaming session in one sitting, without having to use the money or in-game currency.

From: https://www.gamerefinery.com/3-things-to-know-about-session-length-restriction-when-designing-a-free2play-game/