There's
quake2delphi http://www.sulaco.co.za/quake2/default.asp and
quake3delphi http://quake3.delphigl.com/index.php/Main_Page
(assuming you want to count them, since they are not really "native" ObjectPascal engines, just a conversion to ObjectPascal).

<Shameless self promotion>
See also VRML + OpenGL game engine on my WWW page. Not enough advertised now, and the only things done with it so far are my own VRML viewer and small demos. But hey, it's going to be great My entry on PDG (gosh, if I manage to finish it on time) should make a good demo of it.
</ssp>