When I found out that Suikoden Tierkreis existed, I was pretty excited, because.. well, I love the series, but I guess all of the members here do that.
But after I played it for a while, it was kinda disappointing.. I think the only thing that relates to Suikoden are the 108 stars of destiny... and that's pretty much it (except maybe that you get a castle here, too.).
There's a trading system ingame that lets you buy "useless" items from every town, each of them having their own prices, which means you can buy an item from one town for 500 and sell it in a different town for 1500. If you do this a lot, you will not only become filthy rich, you will also unlock new items in shops that you can actually "use", like equipment, potions, etc.
Also you can accept and fullfill missions in this game.
All in all I would say it's an average RPG, but a very bad Suikoden