If you live in the USA, EU, CA or AU, (and most other non-third-world jurisdictions, really), your consumer protection laws explicitly protect your right to withdrawal without loss from digital purchases bait-and-switch scams like these, (including games that permanently become unplayable, their expansions and DLCs, AND digital currency/purchases made within/via said games). Even in countries where you don't have explicit protections to that effect, credit card companies/banks still carry insurance for WAY more than the value+overhead of every transaction - so they're happy to help you unless you get incredibly unlucky with the CSR lottery (... in which case, hang tf up and call tf back).

For the Marks, ask politely for a refund from AGS directly, making sure to include in your request that you are invoking your right to withdrawal following their breach of purchase contract, and that they are obliged by the laws of your jurisdiction of residence to comply. When they decline, screenshot it, and submit it to your card company / bank / payment processor with your CHARGEBACK REQUEST, along with a statement that the seller in question is in blatant violation of law AND in breach of contract AND operating in bad faith by withholding the full refund to which you are rightfully entitled.
NOTE: If you did something dumb like use Paypal or another payment processor instead of a credit card directly—(DON'T EVER DO THAT)—they're all completely untouchable and will likely either ignore you or just say "nah" - in which case, document it, and then rinse/repeat with the actual card company / bank (i.e. the only entity to which they are actually beholden for anything at all).

For the game/expansions/DLCs, ask politely for a refund through Steam—(which, btw, is actually obligated by law to provide them to any purchasers upon request in those jurisdictions - though they are untouchable and thus rarely comply with local or federal laws)—or Amazon (wherever you bought the game) in exactly the same manner and using exactly the same language, and when they decline, do exactly the same thing.

99% of the time, this is all you need to do. It doesn't matter if it was 5 hours or 5 years ago - you can still always charge back any payment made to a company operating in bad-faith and/or in violation of law or breach of contract (all three of which apply in this case)... AND YOU ABSOLUTELY SHOULD!

It happens. People are ultimately still people, and many, MANY people get paid actual money to be idiots at work all day. (... Just ask AGS leadership, or anyone at Steam support). Wish I could land a sweet gig like that.

If your bank or card company declines and stands firm, tell them that you'll call their regulatory agency if they, too, insist on violating the law and your rights; if some incredibly asinine big fish with severe small pond syndrome STILL insists at that point, follow through by actually doing it - and then continue to re-submit your chargeback request as many times as it takes, but at least 3-5 times, even if they continue to deny the request.

WHY (#1):
At the very least, a cursory follow-up is mandated whenever most regulatory agencies receive reports of consumer antagonism/non-compliance via credit card companies/banks. The cost to the bank of EVERY SINGLE INSTANCE of any regulatory agency's follow up/investigation alone is hundreds of labor hours and tens of thousands of dollars, and they'll almost certainly get fined even more for their non-compliance on top of that expense (even though you'll never know about it). Any low-level call center supervisor for a card company knows this, and will be trained never, EVER to allow that to happen.

WHY (#2):
After 3 or more times requesting a chargeback on record for a given account, if they still won't comply, in most jurisdictions you can legally simply refuse to pay another cent toward anything on that account, ever; in the USA, the big 3 credit bureaus are obliged to remove from your record any hint of a company or bank that tries to collect on an account under those conditions - so the worst thing most banks can do to you in the long run if you *legally* withhold payment is to cancel the account and write it off... at their own tremendous expense.

IMPORTANT NOTE: You DO need to be willing to follow-through with the credit bureaus if it comes to that, obviously. This is unlikely in the vast majority of circumstances, but may become a factor particularly if your bank is also unwilling to comply with law and would rather just try to recover the money from you - so as you navigate this process make sure you don't give anyone a special reason to want to make your life difficult, don't try to create additional problems where there aren't any, and in general don't abuse chargebacks frivolously or without legitimate cause... thus the earlier instructions containing the word "POLITE."

Be sensible.

Chargebacks are a legally-protected (and legally-bounded) consumer recourse - not a social engineering tool nor a cost-saving financial hack.

I'd say good luck, but honestly you very likely don't need it. Just be polite, direct, concise, and keep it all business.

I already got my own money back. Go get yours!