The Leadwerks 2.5 is still attractive because of the following -
1. Excellent soft shadows for each light type commands ( functions ) accessible from C/C++ and LUA code. The Leadweks 3.X and 4.X totally lack such commands.( functions ). One can adjust the shadow map size, shadow offset , shadow softness and shadow distance from C/C++ and LUA code.
2. Terrain shadow - this feature of Leadwerks 2.5 is completely absent in Leadwerks 3.X and 4.X
3. Self shadow - Objects cat shadows on themselves and on those that are near to them.
4. Brightness, contrast and saturation - The brightness, contrast and saturation of the renderer can be controlled using C/C++ and LUA code.
5. Larger API set - Leadwerks 2.5 has a much larger set of API function calls accessible from C/C++ and LUA code than Leadwerks 3.X and 4.X making it possible to manipulate almost every important feature of the rendered scene through code without the need being tied to the game engine level editor.
6. Leadwerks 2.5 SHADER effects - Large number of various shader effects developed by the Leadwerks 2.5 community that contains oceans, PBR, TOON, underwater light scattering etc.
7. Leadwerks 2.5 PHYSICS - Built-in support for implementations of mechanical objects like revolving machine parts, vehicles, bouncing objects, damping effect on falling bodies that starts to bounce, realistic floating effect of objects - buoyancy on water planes..
Hope you find the above reasons legitimate.