Last version 0.42_beta, very raw. Why not aviable old map? 0.4 is prototype of multiplayer. So it contain only simple track for chalenge. 0.42 have also prototype of the track constructor. You can download old version. Press "Install game", and next "download direct". This is zipped old 0.3 version.
While no substitute for an actual bike, it does a very good job of giving you the feel of being in the saddle of a DH rig on a mountain where trails are plentiful and somewhat realistic. Once a few of the bugs are ironed out, it has the potential to be even greater!