After the last batch of feedback I've received I decided to change the main game resolution to 1024x600 (previously 800x600). This will improve the quality of the game and also give me more space to use. It also means that the current images from the game gallery will be resized (and hopefully changed). If you have any other suggestions, don't be shy to share them!
Here is a sneak peek of one of the new backgrounds in the new resolution:
