Hi Volker,
We will look into if we can fix anything on our side, but after researching your Mac model it seems like it isn't intended for 3d gaming, which is why the 3d games are probably unreliable. For example from
http://www.macworld.co.uk/feature/mac/b ... g-3446272/
<below pasted in from that link>
Best Mac for Gaming: GPUs in Macs
Apple currently uses a confusing mixture of integrated and discrete GPUs across the Mac range. So, in order to try and clear up some of the confusion, here’s a quick guide to the various GPUs used in the current Mac range (in ascending order of power):
Intel Integrated Graphics:
Intel HD Graphics 5000 (1.4GHz Mac Mini)
Intel HD Graphics 5300 (MacBook 2015 edition)
Intel HD Graphics 6000 (MacBook Air, 21.5-inch iMac/1.6GHz)
Intel Iris 5100 (2.6GHz/2.8GHz Mac Mini)
Intel Iris 6100 (13-inch MacBook Pro)
Intel Iris Pro 5200 (2.2GHz MacBook Pro)
Intel Iris Pro 6200 (21.5-inch iMac/2.8GHz, 21.5-inch Retina iMac)
Discrete Graphics:
AMD Radeon R9 M370X (2.5GHz MacBook Pro)
AMD Radeon R9 M380/2GB VRAM (27-inch iMac/3.2GHz)
AMD Radeon R9 M390/2GB VRAM (27-inch iMac/3.2GHz)
AMD Radeon R9 M395/2GB VRAM (27-inch iMac/3.3GHz)
Dual AMD FirePro D300/2x2GB VRAM (Quad-Core MacPro)
Dual AMD FirePro D500/2x3GB VRAM (Six-Core MacPro)
As a general rule, the ‘Intel HD Graphics’ range used in many current Macs (and many older models as well) just aren’t powerful enough for 3D games. The...
Also in the Alive web page it says you need a dedicated video card. Basically this means not an integrated / intel card. So, your Mac doesn't meet the minimum requirements and isn't designed to run 3d games.
I've heard from you separately that you have this working in Windows, so I would stick with that version for now, or only run the non 3d-game parts of Alive when using your Mac.
Best,
Ryan