Are these games all direct sequels or can I just jump into the series?

I saw Till the end of time (I don't know the order of these games) for 12.99 and I might buy it. Would it be ok to get this without playing other Star Ocean games?

nooo dont buy till the end of time that ending ruined the whole series.

I don't care about story, only content and gameplay.

Storyline-wise its the Last game in the series, but you wont be lost, it was my first SO game, and the best imo. SO4 is good to though.

As for Till the end of Time, go right for it bro, its worth it, gameplay is awesome, and its REALLY LONG, just like all tri-ace based games.

well the gameplay is very frustrating you fight with swords against overpowered enemies or killzone guys. and the synthesis system is a mess . the worst in the series.

Really long?

I'm buying it. Heck this might be better than Tales.

Is there a lot of grinding exploration? (I love RPG's that force you to grind).

Get it. They all take place in the same universe but none of them are directly connected (save for SOBS).

whats SOBs?

You can grind a lot if you want main game if you find the battle system particularly appealing, but post-game can have a fair amount of grinding just to try to max out stats, beat bonus bosses, clear bonus dungeons, trying for 100% battle trophy completion and other junk like that. I'm pretty sure Star Ocean III is the longest game in the series as far as the main game goes and probably post-game too.

A lot of people experience a difficulty spike maybe half-way or somewhat past that in the game, but exploiting the bonus gauge more or less gets you 3x experience ever battle.

SOBS = Star Ocean Blue Sphere, some GBA game in Japan. Direct sequel to SO2.

There is absolutely no grinding required in SO3. Any and all powering can be done through proper item creation. There's a battle trophy that requires you to beat the final boss with a level 1 party. It's entirely possible with skill and the right equipment.

Star Ocean Blue Sphere. It's the direct sequel to Star Ocean 2 released for the Gameboy Color in 2001. Unfortunately it's Japan only but damn is it an amazing handheld RPG.