There are several easy steps to follow to get the game to run smoothly.

(If you know about Compatibility Settings in Windows 8 / 10, scroll down to the screenshot, which will show the relevant settings you need)

In order to make this as quick as possible, I will be bypassing Steam's interface altogether to get the program to work.

Open Windows Explorer and enter the following path in the address bar:

C:\Program Files (x86)\Steam\SteamApps\common\RollerCoaster Tycoon Deluxe

Or, if you are running 32-bit Windows, the path will be:

C:\Program Files\Steam\SteamApps\common\RollerCoaster Tycoon Deluxe

If you are not using the Steam version of the game for whatever reason, just navigate to where Rollercoaster Tycoon is installed.

Next, right click on RCT.EXE, and click Properties. In the window that appears, select the Compatibility tab.

Then, do the following:

• Tick Run this program in compatibility mode for..., and select Windows XP (Service Pack 2) in the drop down box below.
  
• Tick Reduced colour mode, and select 16-bit (65536) colour in the drop down box below. This is to prevent the program not running in certain full-screen modes by forcing the Windowed mode in everything except the Tutorial (which will work as it runs in 640x480). In windowed mode, you can resize up to around 1280x1024.
  
• Tick Run this program as administrator; this ensures that you can save and open files.
  
• Tick Enable this program to work with OneDrive (may say SkyDrive on some systems) files; this means you can save your RCT games in the cloud!

Once you are done, the tab should look like this:


Now run the game as normal through Steam, and everything should be fine.

Now, your game should work

You might want to try disabling the Steam overlay for the game. Luckily, this is very easy to do.

Go to the Library tab in Steam, and find RollerCoaster Tycoon Deluxe in the left column. Right click on the name, and select Properites.

In the General tab, there is a tick box, which says Enable Steam overlay while in-game. Unitck this box and select OK - run the game as normal and see if it has fixed the problem.

If it has not, then there may be a more complex problem afoot.

This is a very easy problem to fix (and is one that happened in Windows 7, Vista, and even XP).

When you exit the game, make sure you right click somewhere. This should re-activate the left mouse button. Repeatedly click between the two buttons if it doesn't work immediately.

The reason this happens is because of the unusual way RollerCoaster Tycoon takes control of the mouse pointer during the game, and the effects of it can be residual once you exit the game.

I hope this guide was useful, and stops you having to scour the web for a working solution.