ARK Evolved, 80% off on Steam.
Cheapest for a while now. Was 16 AUD some time ago and a long time ago it was for a brief moment AUD $10, but for the last month per price trackers, it has been stubbornly around AUD 70. CD keys is north of AUD70.
My 11 year old has been nagging, so glad to see the price come back to earth.
ARK evolved is best described as Minecraft with better graphics and dinosaurs. Survival, Crafting and taming animals. Free on iPad. Better experience on PC.