Spellcaster is easily in the top 10 best Sega Master Master system games, but no way could it be confused with a Phantasy Star game. It's a combination adventure/action game. When you're in a location you have a static picture and a menu with things like "Look", "Talk", etc.... If you've played Snatcher for the Sega CD it's really similar to that. There were a ton of computer games in the 80s to early 90s that were like this too. That view is not drastically different than when you talk to someone in the original Phantasy Star I guess.
When you travel to a new place, or have to go deal with enemies, then it's a side-scrolling action game. You have different spells you can use and it's hard as
. Here's where there is no similarity to Phantasy Star.
The info in this article is just plain wrong. I don't even think it's possible that Spellcaster was originally a Phantasy Star sequel that was converted to a standalone game. The setting and artwork is completely different. *Maybe* if it took place in the future or on an alien world but it takes place in early 1900's Japan (don't quote me on the date, just a guess based on memory).