Construct 2 is actually a complete game engine that I often mention to artists or designers who want to experiment with their own projects. The free version has plenty of features and the pro and commercial versions are affordable, too. It uses an XML project format so importing a Pingus level is quite straightforward:
Editing and scrolling are very fast and I like the controls for placing and moving objects. When I wrote the importer it was mildly irritating that many of the XML tags have a dash in them, which breaks word selection when copy and pasting tags into sourcecode.
Construct 2 manages sprite and animation bitmaps itself, which may add a bit of extra work if you want to manage your own sprite sheets for editing. You can add your own properties to an object type.
It would be useful if you could group layouts or object types into folders, because the flat lists get a bit awkward to browse in a huge project.
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