hey there!
the number you're seeing in the error message is the amount of "ticks" that have passed in the saved games you've got. 25 ticks = 1 in-game second, and at fastest game speed, an in-game second is roughly 0.4 of a real-life second. it's just a way to tell you when the crash occurred, for debugging purposes
game data invalid is what it sounds like, unfortunately. something in the save file ain't playing nice with the new exe. we try to maintain backwards compatibility, but ya know how development can be
the good news is, you should be able to run any mission made with a prior version of the game in mind just fine between stable versions of the exe. there are minor exceptions, like if a bug was exploited for map design and that bug was fixed, the map that used it may be a little different. nothing should be unplayable though
and, you should also be able to run more modern campaigns making use of the powerful new features. Cm's index has all known playable content documented:
and if you'd like some examples of more modern campaigns, I can make a few recommendations of threads to check out via that index:
- Thel 'Vadam Flippy's Great Battle of Arrakis focuses heavily on large-scale macro missions, using some powerful variables-based features, such as 'repeat queueing' to let you mass-produce large armies to clash with
- PsYcHo's Smuggler Restructure campaign is closer to vanilla in terms of most of the event types used, but makes use of minimap pings and quite a few lovely new units he created as voxels, which I later polished up
- my Summers' Solstice campaign recently had some new features backported to it. nothing that fundamentally changes the missions, except ooone thing on the final mission, but some significant optimizations and QoL
but there are plenty of gems besides those; these are specifically campaigns that use new features with the v2.3 exe and all that
on a tangential note, the very latest mission designed for d2k at the time of this post is the Arkanon Debut mission included in that tileset's thread. it'd be under "single missions" in the index. that uses a cutting-edge exe though, technically not the stable version of 2.3. still, it might be of interest if you're looking to get a peek at the most modern of our capabilities
anyway, I hope that answers your question!