Comment by toast0

Many of these get stuck in contract hell. The original developer may have had licensed software or assets and at the very least needs to find the agreements and understand how they work for new distribution. It's not uncommon for those agreements to have been time limited, but if you want to renew now you need to find the current successor/rightsholder and negotiate.

Also, the developer/publisher/distributor/etc may have had revenue sharing agreements with various parties. Those need to be found and understood too. Sometimes those are in % of gross income, % of net income, % of sales price, or a fixed amount per copy sold. If anything needs addressing, you've got to find those parties or their successors and negotiate. You should also find those parties anyway, to pay royalties they're due, but if you at least set up an escrow account, you'll be prepared when they find you.

I would hope games contracts are a bit more forward looking now, and try to address these things, but 25 years ago, you would still get old games at computer surplus stores... A handful of developers would put out old games collections, but most games never came back.