For sure Leadwerks is Blitz3d related
It supplies pratically the same functions
I have been using Blitz for 4 years
One of the best engine ever
With a bunch of functions you can accomplish pratically every task,even without reading the manual, every thing being so intuitive

I quitted with Blitz because :

- the rendering engine was outdated ( direct x 7.0)
- it was lacking a world editor
- the scripting language was basic based

Leadwerks supplies also the excellent 3d world studio ( cartographi shop)
The script language Bmax is OO
You can use also C++ or C#

LaedWerks might be the right solution for serious amateurs