The HZ Engine is a real-time action strategy engine by David Jeske. Download There are pre-alpha binary snapshots available from the download link above. However, be warned that this is not a playable game.
Much work still needs to be done.
There is also a GPLed source release. The engine only specifically deals with layers, as they are tied to specific rendering functionality. UI View Heirarchy, allows easy placement of items, also handles event delivery. 2d hardware blitter support via Windows DirectDraw. Currently, some of the artwork is rendered from 3d models, but the tilesets and a few other pieces are borrowed from other games.