In-game free spins
The commonly used terminology can be a bit confusing so it´s important to note that in-game free spins are no the same thing as regular free spins or RealSpins. In-game free spins is a special bonus feature that is triggered by hitting certain symbols in the game. Most video slots offer a free spin feature and it´s more often than not triggered by three or more scatter symbols.
Example from Mega Fortune:

When you hit 3 scatters anywhere on the reels while playing Mega Fortune you activate the free spin mode. You must now click one of the scatters and your reward will be revealed.
What games offer in-game free spins?You can see the complete selection by clicking on the "Feature" drop down in the game filter and ticking «free spins» in our game filter.
Free spin games
The in-game free spin feature is available on slots from Net Entertainment, Play N Go, Yggdrasil and Quickspin.