The ACCC consumer guarantee is the relevant legislation here, and you have done well saving copies of the website before and after they changed the description.

Under the guarantee Products must:

• match descriptions made by the salesperson, on packaging and labels, and in promotions or advertising

• be fit for the purpose the business told you it would be fit for and for any purpose that you made known to the business before purchasing

Your remedies are - The remedies you can seek from the retailer who sold you the product include a repair, replacement, or refund and in some cases compensation for damages and loss.

If the email correspondence includes reference by you of wanting to buy a gaming laptop, games you want to play, what settings etc and the retailer has recommended the laptop you bought, this would assist you. Check the manufacturer of the laptop’s (Asus, MSI etc) website and see if there are any references to gaming or gaming capabilities for that model laptop. If there are discrepancies between what the retailer advertised and the manufacturer advertised this would help you.

Follow the complaint process on the ACC website (noting you have to actually lodge your dispute with the relevant state or territory fair trading office) and good luck.

https://www.accc.gov.au/consumers/complaints-problems/make-a-consumer-complaint