Ok.. Here is what I would speculate based off the HTG request.
There are two points of contention. Abandonware vs original content.
Now, as it relates to abandonware, unfortunately no, it doesnt work. The reason being is that for it to be officially considered abandonware basically one (and usually more)of several possibilities must occur. A: The original developer no longer exists. B: The original publisher no longer exists. C: The organization who holds the copywrite no longer exists, D: The game is no longer sold for profit (as in the dev/pub/CW holder have modified the license to be freeware/shareware) E: The copywrite holder has made no sort of attempt to gain financial renumeration from the product within a span of no less than 10-20 years.
With this specific entry, I do not think it would fly off of abandonware principles. Both the publisher and developer of the game still exist. Sega specifically IS an organization that is highly invested in the market, and is notorious for trying to make profit off of old existing properties. So the likelihood that say next year, they might want to release an online phantasy star collection is realistically possible.
The other issue is private servers as it relates to user generated content. It truly depends on the level of work involved in the modification of the game. If the game is basically identical but with a few dozen stats modified, or different starting items, then no, it doesnt have a leg to stand on, because its just a mod, not a fully and original creation. However, if you have things like new cut scenes, new voice acting, new narrative, new graphics, etc, then its possible you might be able to get away with it.
However, the real question is.. do all parties have the original discs to extract the base game files from? If so, opening up a private server is not specifically piracy. However, if someone is redistributing the files, then its a just lighter shade of black area described above.
Either or, Its really not worth all the aggravation for a 10 year old game is it?
EDIT: and please remember, I am not condoning it, Or suggesting how to shirk it. More to the effect of trying to explain how most legal eyes would see it.
