The reason behind this is that the video drivers for mac are missing something that require shaders to work (its not Badspot's fault, he can't fix it). To see what this is set shaders to anything above minimum load a map such as the tutorial and once you spawn in press the ~ button and there will be a list of things that require shaders followed be something like "YES" or "NO" (I dont really remember).
I have said this many times and the only way this is to be fixed is if a bunch of the Blockland community members (mostly mac users as, not to sound harsh but its their problem) send e-mails or contact apple support or something about including this in their video drivers however I dont think anyone has spend their time doing this.
This so much. Don't tell him his computer can't handle it because it's a Mac, guys... Give him the real reason, or don't give him anything. Apparently, there have been a few cases where shadows actually have worked on Macs; these are just rare. It's not that the hardware is bad; in this case, it's a software/driver issue. My Mac runs plenty of other games just fine, and while it is by no means a beast of a gaming computer, it also by no means sucks. And it's a 2008 model, so it's not like it's all that new.
The world will be a happier place when people stop fighting over PCs.
