The free Games with Gold and PlayStation Plus titles for April 2018 were revealed from both Microsoft and Sony. Let's start with the Xbox games.

The free Games with Gold for April 2018 include The Witness, Assassin's Creed Syndicate, Cars 2, and Dead Space 2.
The WitnessCars 2: The Video GameDead Space 2

That's a mostly solid lineup there. Now, on to the free PlayStation Plus games. In April, PlayStation owners will get to pick up Mad Max, Trackmania Turbo, In Space We Brawl, Toy Home, 99 VIDAS, and Q*Bert Rebooted.
Mad MaxTrackmania Turbo