Overall, my expenses for this hobby far outweigh any minor profit that I've made occasionally selling a game. This is what HR Block says:
"IRS guidelines state hobbyists sell items occasionally, not intending to make a profit from their activity. Hobbyists may deduct the expenses related to their hobby as miscellaneous itemized deductions, but not beyond the total revenue generated from the hobby. And, only the amount in excess of 2 percent of your adjusted gross income is deductible.
If sales become frequent activities done to make a profit, the IRS may classify that hobby as a business. If the taxpayer is the sole proprietor, purchases and sales must be reported on Schedule C. A tax benefit of operating a business is that ordinary and necessary business expenses can directly offset income and a loss can be shown.
No matter what is sold (it’s a treasure to someone) or how often, all taxpayers who make a profit on a sale are obligated to report that money as taxable income. Determining what your tax obligations are for any sales you make can be determined with the guidance of a tax professional."
https://www.hrblock.com/tax-center/income/other-income/capital-gains-garage-sale/