Overview
First of all, you should know that this is a workaround and it’s not possible to directly post screenshots to Steam from the ‘Original’ game since it doesn’t support the Steam Overlay.As you can see below, I’ll describe in steps what you should do to make it possible!Tip: Before you begin the steps below, take some screenshots of RCT first. You can do this by pressing PrintScreen (or ALT+PrintScreen if you’re in a window) on your keyboard and pasting them in Paint or Photoshop.
Try it
1. Install VLC Media Player[www.videolan.org] (Other software might do as well, but I used VLC).
2. Add VLC to Steam as a Non-Steam Game.
3. Search for VLC in your games list. Right click it and cxhoose ‘Properties’. Change it’s name to the exact same name: RollerCoaster Tycoon: Deluxe.
4. Start VLC using the Play button in Steam.
5. Play a file and go to fullscreen (try a double click).
6. Press F12. It should take a screenshot (If it doesn’t, try going into the Steam Overlay first by pressing the ‘default’ Tab+Shift).
7. Exit VLC.
8. A Screenshot window should open. Click on Show Files On Disk.
9. Here, you can edit them all you want and change them to your preferred screenshot you’ve taken earlier.
10. Upload your screenshot! If you did well it should show up in your timeline just like you’d see from the original game.
I hope this could help you! If you got any questions or it didn’t work for you, let me know and maybe I can help you out 🙂