New Ride/Attraction Now Available
On August 14, 2010, fans of the RollerCoaster Tycoon games were asked by Atari officials (through their forums) what they would like to see implemented in a fourth installment of the game. They also stated that they were "thinking hard about the next RollerCoaster Tycoon game on PC". Many fans assumed that this meant a fourth installment was in development. However, this was not true and Atari took down the thread.
In 2013, RollerCoaster Tycoon 4 was supposedly announced to be under development by Red Coin Games, with a trailer on Youtube. However, Red Coin Games has confirmed that this trailer is fake, no word on if the actual game is in Development. Though some claim to have heard rumors of Dreampark Studio to be made by Red Coin Games.
On 11th March 2014 RollerCoaster Tycoon 4 has apparently been teased by Atari on their Facebook and Twitter pages and it could be a mobile game because Atari had a post saying #RCT4M 
A fourth installment in the series was announced on March 16th, 2014
As of 3/18/14, Atari has announced on their twitter that Roller Coaster Tycoon 4 computer game is in development, and a mobile game will be released soon.
The trailer for the mobile app got extremely negative reviews. Over 5000 dislikes in just days after posting. As wall as whole pages of hate comments. As a response to this, the Roller Coaster Tycoon facebook page said this, " We hear everyone’s comments on the new RollerCoaster Tycoon game and want to let you all know that the mobile game and PC experience will be 2 completely different games. Both games will release this year. The mobile game will include social features (sharing with friends, leaderboards) and the PC experience will have even more features and functionality. We are excited to bring these games to you soon! "
People were still worried about the PC game not being of decent quality due to the 6 months development time. Although, we have nothing to go on past these rumors since there is no video or more information of any kind, about the PC version. RCT4 Mobile was released on April 14, 2014.