Hex Gettysburg is the 1961 version of Gettysburg published by Avalon Hill. The square grid and movement templates from the 1958 version are gone. Gone also are the rectangular unit counters. Instead, players have a classic hex grid, along with normal square unit counters. This version was panned badly and did not survive in the AH catalog for long. The square movement grid was returned in the 1964 version of Gettysburg.
This description courtesy of user Soltan Gris.
Added by Steve1501. It was panned badly because the units moved way way too slow. Inf. could move just 1/3 mile per hr., when Inf. can easily march 2.5 miles per hr. on a road and Inf. can move 1 mile per hr. off the roads. This made it impossible for history to be recreated. It took all the 1st day for the Union I Corps to arrive near the town when it historically arrived at the battle site NW of the town at about 9:30 AM.
The 2nd major problem was that it allowed stacking of 2 Inf. Div. in a hex. Two Confed. Inf. Div. would total about 16,000 men. This works out to about 18 lines of men 1 deep or 9 lines 2 men deep across the hex. The maximum number of 2 deep lines that could help attack or defend a hex would be 3 or 4. So, the rules allowed 3 times the reasonable stacking in the hexes. Again, not historical.
There were other problems. The Artillery rules were unclear. Units were doubled in Hill or rough hexes even when attacked from the same hill. There were no wooded and hill hexes. There were way too many woods hexes on the map. There were no rules for enfilade attacks. Etc.
See the main AH Gettysburg page for what can be done at this late date to use it. End edit.