This game is......HELLA WICKED AWESOME SICK COOL!!!! Now watch out for puke and I will walk you through the game.
As you carry out your missions you unlock new missions and eventually other theme parks. Basically the games breaks down into two segments. Building crap and playing games. In each zone of your park you will build some rides, some games, and some stalls. Each zone of your park has a power limit and you cant exceed it and everything requires power. Coasters and carnival rides are the biggest energy suckers. So if your smart you will try to balance all the stuff you want to build across your 3 zones. After you get done building crap is when thereal fun starts. Thrillville has all these cool minigames in that you get to play and challenge other people to. Some of them really suck and some of them are pretty cool. They added some new minigames to Off the Rails like this awesome WW1 or 2 fighter plane game called Sqaudron Ace. You can also play this game called coastertron that lets you fly along any of the coasters you have made in virtual space and try to touch these rings and stuff(i suck at it). The stalls where you sell food and merchandise also have a minigame built into them which makes people buy stuff.
You also have to hire cheerleaders, groundskeepers and maintenance workers to keep your park a fun happy place. In order for them to do the best job possable you have to take control of them and play these minigames which are fun.
Building Coasters is awesome. Some are made out of different materials which determine what kind of things you can do to the tracks. Like one made out of steel is super bendy twisty while one made of wood would be not very exciting. The new thing they did was add these WHOA! pieces. Whoa pieces are anything from loop to loops to giant up/downward spiral pieces or new things like fire hoops, bricks walls, or insane crap like a cannon that shoots your ball shaped caosters through the air or a crane that picks you up and moves you over to a different section of track, or cool lift mechanics that kind of picks up all the cars and dumps them onto a downward vertical track. There are alot more.
You can also make vehichle rides for go-karts, hover-carts, monster trucks. They work basically just like coaster but you have alot less options because you get to race against other people and move all over the track.
Each zone of your park has 2 platforms. One is specifically for coasters and the other one is a coaster/track. Your power limit will be the biggest factor in designing your coaster but there are two other important things. The game keeps track of a ton of things about your coaster and all the things it keeps track of determine how thrilling your ride will be but it also determines how sick it will make the riders. Slam your riders with to many G-forces and they will barf all over your nice park(which shouldnt be a problem if you have alot of groundskeepers) but your guests have needs and some might not like rides that make them sick so it wont make alot of money. So you have to build coasters with your guests in mind.
How the hell will you know what your guests want? Well you can overhear them talking sometimes but you can also walk right up to them and start a conversation and ask! You can also fall in love with people and give them presents or challenge them to play any of your games. You basically do the same thing at each of your parks but the missions get a little more challenging. Between building coasters/tracks and playing the minigames I think the game is super fun. The best part is if you have someone else to play with you can both compete at the games and stuff. Oh you even get to ride your coasters after you build them in singleplayer. You can experience your ride first hand in first person mode or you can zoom out and see the car/train
I dont know if this game is worth full price, but I think its one you should definately try to own. I hope and pray that Lucas Arts/ Frontier keep making this series because i love it!