July 15, 2015 at 16:17The mystery of large stats in the UFO: Enemy Unknown (1994)
Most of us, who have long played the good old UFO: Enemy Unknown, have encountered (or at least know) cases when the statistics of a soldier flies for 160 and rushes to values that overflow through 255 and go to zero.
I wanted to clarify the situation, why this happened, and where exactly this happened. In order to put an end to this story.
During the study, DOS versions 1.0, 1.2, 1.4, Russian (translated), and Gold Edition were checked. That is, literally all available.
This glitch was observed onlyin version 1.0. But, it is worth noting that the Russified version was based precisely on version 1.0, so it turned out that our many compatriots faced this situation much more often than in the rest of the world, because it slipped only briefly (patch 1.2 came out quickly enough, just a month later), and no one did the Russification of fresh versions.
A fragment of the geoscape.exe disassembled code, which is responsible for increasing stats based on the mission result (increasing Time Units):
Offsets 2Ah and 35h relate to Base TUs and TU Improvement, respectively.
In version 1.2, the code already looked slightly different:
Note the key here is JZ / JLE .
JZ - transition if the result is zero (equivalent).
JLE - jump if the result is less or equivalent.
It turns out that initially the developers made a beginner’s mistake: they checked for a limit without a margin, despite the fact that the value can jump by more than 1.
That is, in the case of “TUs”, growth was limited only if it definitely hit 80.
Everyone who played in the updated or not Russified versions did not encounter this glitch.
PS: After delving deeper, it turned out that the Russified version was a hybrid in which GEOSCAPE.EXE was taken from version 1.0, and BATTLESCAPE.EXE was from 1.2. It’s just that the warhead from 1.0 crashed when the Crissalids appeared, and with this version the game would be unviable. Gollops deliberately divided the game into two different EXE's (two different game modes) interacting via files in order for the game to fit in 640 kilobytes of Conventional Memory, well, for historical reasons: it was originally conceived as a simple turn-based tactic, Laser Squad 2. Therefore, such a hybrid was possible.
