All Tom Clancy's Splinter Cell Games Are Discounted (prices range from £1.35 to £2.71 per game) @ Xbox Hungary

Yep, totally different games. The Xbox/PS2 games were made by Ubisoft Montreal (who did Chaos Theory) and the 360/PS3 games were made by Ubisoft Shanghai (who did Pandora Tomorrow).

Original Xbox version (aka V2) is usually considered the better of the two for a few reasons.

The gameplay is essentially identical to Chaos Theory which is universally agreed to be the peak of the franchise. The level design isnt quite as polished, but the missions are longer and are generally mostly at night which is more traditional Splinter Cell. It plays the same & Sam moves/controls the same.

Story wise, it's less cinematic though told via flashbacks before missions, otherwise the way the story develops is more like the first 3 games.

Double Agent on 360 (aka V1) is usually considered the inferior version overall, but it does do some things better than V2.

Gameplay is less fluid; it is still clearly built off of Chaos Theory, but movement is much less precise & a bit janky... although it's not as bad as Conviction/Blacklist end up becoming. It still feels like classic SC, but it's still a step back. Likewise, missions are shorter, have inferior designs, and more are set during the day compared to V2.

That said, it isn't all bad. It adds new gameplay elements like corner grabs, the return of the laser mic, several new gadgets like a fingerprint scanner & minigames like safecracking; etc.

Story wise, it's... fine. It misses some context that helps explain why certain things are even happening but since the plots are more or less the same, it's still a serviceable story. Graphically, the game was always better but not sure if this is still relevant with them both getting the 4K treatment on the Xbox One / Series Consoles.

Get both 👌🏼 (edited)

I think the things that constitute TOS violations are using VPN's with Xbox Live. (edited)

Nah, the MS store and your account keeps currency separate, so your GBP credit can only be used in the UK store.
Sort of like if you redeemed a $10 Xbox Live voucher, it could only be used to purchase on the US store.

But you could maybe buy 1 or 2 on the UK store with your voucher, then get any more you fancy via Hungary, per the post. (edited)

The sale on these games ended yesterday morning (weekly sale runs Tuesday to Tuesday, prices normally revert around 11am) but the SC games go on sale very regularly.

Maybe not all at the same time as above, but you'll probably see at least a couple of them back on sale in the next 2-4 weeks.
Maybe the spring sale will put them all back on sale again.

You need like a starling card or similar. You can Google to get a use able address to copy and paste