Recs.
Updated
Parkitect is a simpler indie theme park game more in the vein of the original Roller Coaster Tycoon, and aims to be a spiritual successor to the 2D original.
SpecsUpdate
Pros
Pro Easier and quicker to create interesting parks
Since the park builder works on a simpler isometric grid system it's a much easier game to learn and get into and this simpler system makes it easier to build things. Although the final level of detail is lower than other modern theme park builder games, you can build out more things faster than you can in the other games.
Pro Decorations can be placed off grid
You can achieve much more detail than you could in the original Roller Coaster Tycoon games because objects can be placed anywhere even though they default to the grid, which gives you the ease of grid building with the flexibility or placing objects anywhere.
Pro Developers are very open about the process
The developers have a blog where they post development updates and are very open about all the things they are working on and the steps to completing the full game.