I've created a two-part 100% walkthrough video. It covers every single achievement in the game except the co-op ones and the speedruns, but the co-op are self-explanatory and the speedruns are super easy once you've played a level, since you can usually just run past everything and solve the puzzles most of the time. Contrary to some reports, you CAN get the gold points challenge on EVERY tomb on your first time through in solo play. Follow along with the video below as you play through the game (and part 1) to have your 1k in 8-10 hours tops. A detailed text guide follows after the time stamps for those that prefer it, copied over from the walkthrough I've written for this game.
This achievement is story-related and will unlock when you defeat the Pharaoh.
Timestamps:
0:07 - Tomb of the Lamplighter
13:55 - Tomb of Sobek
18:20 - Challenge Tomb #4
19:12 - Tomb of the Architect
29:44 - Tomb of the Torturer
43:11 - Pharoah
45:32 - Tomb of Set
51:29 - All Hub World Red Skulls
You’ll be tasked with dealing with the Pharaoh before the final faceoff against Set. Pharaoh’s tomb is at the very bottom-left of the map, so head there now. If you recall where the fourth cog was that you had to free from ice for the Tomb of the Architect, head there and go south. Strangely, this tomb is the only one in the game with no challenges to complete (apart from the challenge tombs, which don’t really count). The fight itself is very simple. Just shoot him to death, avoiding the blue flame vents on the floor, which are preceded by a glowing warning before they activate, making them easy to dodge. At the end of the fight, you’ll get the final piece of Osiris, restoring his dominion over the cold, and unlock That’s a wrap. You’ll be tasked to return to the pyramid and defeat Set, with Osiris’ assistance.