@TheQuin
I have a small idea like the one below but I don't know whether this can be applied or not

we can combine simple image and math
for example like this
we can ask the users who will claim the free rolls game to enter the results of the math operation from the last 1 digit of their balance according to the instructions in the captcha

example 1
instructions in captcha: "your last digit + 2"
then the correct answer for someone with a balance of 0.04497642 is "4"

example 2
instructions in captcha: "your last digit * four"
then the correct answer for someone with a balance of 0.04497642 is "8"

but someone who has a balance with the last digit "0" if he gets a mathematical operation "*" then the result will always be "0"
so maybe we should only use "+" and "-" in the captcha

with the last digit of the user balance I think it will make "a little" sure that the person who completes the captcha is the owner of the account (a bit similar to the checksum)

of course it won't last forever
they will definitely look for new ways to integrate
so we have to change the method in a certain period, for example 1 or 2 months
this will be a little like how Monero is fighting the ASIC device

but again I don't know if this is possible or not