Hello!

I have all EPs and all SPs, but there is one question from me.

For example I have Base game, Pets and Celebration stuff, why do I must have to run Pets instead of Celebration stuff?

because the engine runs off the most current EP which is pets in that combo. A stuff pack like celebration is just that it puts more items in your game but doesn't have the game engine so even if it came out after pets the last engine is pets until you add a later EP.

But some years ago I had Celebration as latest SP and had pets, I had to choose Celebration stuff to run the game.

Yes, Celebration and Family Fun Stuff, back in the day, did update the engine and so you had to use them to run the game. When you talk about having base game, pets and celebration now, did that come in a compilation edition of the game? Either that or you have an updated version of Pets which has the updated engine.

The compilation Fun with Pets comes with Pets, Family Fun Stuff, and Mansion and Gardens, with M&G being the last and most updated game engine. So if they install that disc with pets but not M&G theyt would still need the compilation disc and not celebrations.

If you had celebration stuff installed without Seasons then it would ask for the celebration disc because it would have the updated game engine because it came out after Seasons, though I thought the only stuff pack that contained a game engine was M&G because it was near an EP level?

TBH I don't really know, as I only collected the SP's like 2 years ago and only the ones that didn't come with the 3 compilation discs.

There were those two SPs early on that did contain an engine update - a bit like a patch really but added on to the SP rather than released separately.

The game did consider some of the SPs to be the needing the CD to run. I remember having to run my game on some of them, but I can't remember which ones. Maybe FFS or Glamour Life.

M&G is considered more to be a "mini-EP" so if you have that one, that's the CD the game runs on.

I started playing with Double Deluxe, which consists of base game, Nightlife and the Celebration! stuff pack. Subsequently I added Open for Business (OFB). To start my game, I have to have the Double Deluxe DVD in the drive. The witty little sayings that appear towards the end of the load process are all about weddings and parties ("Grooming grooms", "De-inviting Don Lothario", "Happy 14th Birthday Reticulated Splines", etc.), and, if I view processes running in Task Manager, it says Sims2SP4.exe. If I try to start my game with the OFB CD in the drive it tells me it's the wrong disc.

I had some correspondence with Mootilda about this in this thread (mainly post #14 and the following posts). This post by twojeffs on Simbology (linked to by Mootilda) is also helpful. As I understand it all the SPs (except for the Holiday packs) come with their own version of the game engine. They all have their own version numbers which you can see in the top right hand corner of the screen in Debug mode. But most of them are only slightly tweaked versions of the EP game engine on which they are based. The exception is Mansions & Gardens which I think added one or two animations or similar features not found in Apartment Life. Mansions & Gardens is certainly the only SP for which Maxis made a patch. [CORRECTION] Maxon and Charity are right: there is no patch for M&G, only for Family Fun Stuff. I don't have either and I mis-remembered.

In short Mootilda's post #17 in the MTS thread I just linked to contains a list of all the version numbers. twojeffs' first post in that Simbology thread tells you which EP game engine each of the SPs is based on.

I thought there was no patch for M&G?

There is no patch for M&G. Family Fun Stuff was the only patched SP.