The simple answer is, no, it's not required. However you do need to make the distinction between revision and version. There are three versions of the game (DL, DA and TA) and there is certainly no requirement that everyone purchase every expansion pack.

Also even though someone may have the latest expansion pack they still have the ability to play and submit games to the metaverse using any of the three versions. I know a number of people that play all three versions of the game. As far as I know this is a perfectly legitimate choice.

As far as revisions, most people do keep pretty close to the latest revision of whatever version of the game they happen to be playing.

For example, I personally still play DL v1.4x. I have been assured by Kryo among others that DL v1.4x is functionally indistinguishable from the latest DL rev which to the best of my knowledge is v1.5. The reason I still play v1.4x is that is the latest version for which a standalone installer was supplied and I object to installing SDC/Impulse on my PC. The claim that v1.4x and v1.5 are functionally equivalent has been demonstrated by the ability to load and continue games saved from one version to the other.

If you’re suggesting that once DA came out that people should no longer play DL or that with TA now out people should no longer play DA or DL then I strongly disagree with your premise.

You suggest that people “keep using an older version with known exploits and score easy points”. However this is incorrect on multiple fronts. First in the case of DA and DL it’s been well documented that it’s easier to get higher scores with DA than it is in DL because of the greater numbers of planets that occur in DA. Also the assumption that DL as an older version has more “known exploits” than DA is highly debatable. For example it’s very clear to most expert players that diplomacy is more exploitable in DA than it is in DL.

What is fair to say is that game version must be kept in mind when making score comparisons. DL games should be compared to DL games and DA games to DA games. Generally most folks keep this in mind as well. However between DL and DA the scoring differences are really not all that major. As I mentioned DA should generally outscore a comparably sized DL game, but on the other hand the economy and morale is a bit easier in DL. The end result is that someone’s score is more dependent on the person playing the game than on the version they’re playing.

For example in the Metaverse League (MVL) we allow games to be played in DL or DA and have just added TA to this mix in the latest round. In the MVL we rank games on both speed (in game years) and score. There has been no noticeable advantage in score or speed to playing DA or DL.

Since we have no real experience with TA it still remains to be seen how that relates to games played in DL or DA but I still suspect that speed and score differences will have far more to do with the ability of the player than it has to do with the version of the game that they’re playing.