This achievement has been fixed on the Windows 10 version of the game in 2022 and is now obtainable as normal.
Not too difficult to get when you know the levels well.
Use the card exploit to obtain as much gold/platinum/permanent cards as possible, selling the big head and rainbow stuff to avoid full inventory. You'll want to try and use a combination of the following cards and as many of them permanent as possible
+100% First Aid: Health Regen disabled; healing items required
+100% Empty Magazine: Start with no ammo
- 50% Toxicity: Unlimited Poison Arrows
+100% Armour Plated: Enemies have double armour
+100% One Life To Live: Forced restart if you die
Total: 350% total score increase at the end of the level
Survivor difficulty will make enemy kills score 3x, and except for the Copper Mill stage you will blow past the gold requirement by 2x, 3x or more, even without making a full chain combo. Toxicity negates the Empty Magazine as is the only weapon you'll ever needs outside of a handful of bosses (Elite Flamethower needs the shotgun for example, final boss needs Y button Melee attacks, perhaps one or two other exceptions I can't think of right now).
You can also boost your combo easily by just killing random wildlife like rats, rabbits and squirrels in the level easily with Poison Arrows (except for birds who seem immune to poison for some reason).
The video I used for Copper Mill was the one in the TA walkthrough:
As long as you make it to x99 combo for a few minutes, you'll be fine.
I did an extra bit to help with this which isn't shown in the walkthrough. At 08:20 in the video, they pull the barricade off of a slippery floor section but don't go through it. I did, jumped at the end, headed left and looped back round for significantly more points (also helps a lot if you lost your combo somewhere before to try and get back to x99).