Here are two black and white scenarios: Downloading a game off of the Internet, playing it, and never paying it. Obviously unethical. Going to a store, buying the game, and playing it. Obviously ethical. Now here are two scenarios that are slightly more grey:

Downloading a game off of the Internet, playing it, finding out you really like it, and going to the store and buying it. I claim this is still on the “unethical” side, although it's obviously not as bad as just downloading and never paying. If the software vendor provides a free trial of their game, that's what you should have used to determine if you would have liked the game or not. If the software vendors does not provide a free trial, that means that they don't want you to try the game before you buy it, and regardless of the wisdom of that marketing strategy, by “trying out” the game ahead of time, you're doing something you're not supposed to be doing.

The vendor asking you never to buy used copies of the game, because the money doesn't end up in the vendor's pockets. Okay, so asking in itself is probably neither ethical nor unethical, but I don't think the vendor's expectation for you to always buy a game new is reasonable. I understand what their argument is: Image someone buys a game for $50, plays it, beats it, get tired of it, sells it to someone else. They play it, beat it, get tired of it, and sell it to someone else, and so on, until 10 people have played it, and the vendor only gets to pocket $50. It's an unattractive scenario for them. However, my response to that is “Don't design games in which people will get tired of them and sell them”, or else “Sell your games a lot cheaper.” $50 is actually quite expensive for a game, IMHO. I buy used PlayStation 2 games off of eBay for about $10-$20 each and I get some really great ones like Metal Gear Solid 3: Snake Eater. It's a fun game, but I wouldn't pay $50 for it. If they sold MGS3 in stores for $20, I'd probably buy it from a store rather than eBay, 'cause then I don't have to worry about getting fucked, or shipping and handling, or stuff like that. And from the sellers perspective, maybe the only reason the seller was willing to pay $50 for MGS3 in the first place was because he knew he'd be able to sell it for around $20 later on on eBay.

So here's a scenario I've only conceived of today, and I am unsure whether it is ethical or not. I buy a game from a store for $50. Now I figure if I open the box, install the game and play it, I probably won't be able to sell it for much more than $20 on eBay, as it's “used”. However, if I keep it mint condition, and never actually open the box, I might be able to sell it for $40 or so. So what if I legally buy the game from a store, but then never open the box, and instead, download the game off the Internet, and play the downloaded version instead? I've already paid the software vendor for a license to play the game, and I figure there's nothing inherently unethical about actually selling the game after I'm done with it. But am I somehow harming someone, somewhere out there, if I employ this tactic?