A quick starter on some of the maps available compiled by Bill Leeson
The British Library contains a number of maps. Sadly they are not yet available on line. To see them you have to visit the library in person, obtain a readers card and order them in the maps and chart room. Where possible a link to the library catalogue page is shown.
1874. Plan fur das Detachments Kriegsspiel, Meckel.
These are 8 inch to a mile or 1:7500 scale war game maps. Maurizio Bragaglia has found a smaller version for Strategic War games. (British Library Maps. Shelf number 6 d 14.). Link to the full catalogue page.
Hills East of Dorking, Hills West of Dorking.
These were 6 inches to a mile maps which were used by the British Army for war games. (British Library Maps shelf number 37 b 48). Link to the full catalogue page.
1866. Neue Plane fur das Kriegsspiel und fur Benutzung fur Taktische Aufgaben.
Herr Oberst Freiherr von Pidoll 1:7200. ( sheets for the Austrian Army K. See July Militair Zeitschrift 1865, also Streffleur Vol.1 p 381 1865. (British Library Maps shelf number 27727 (42). Link to the full catalogue page.
1866. Military Tactics.
A series of six maps to illustrate various military tactics. British Library Maps 999(92).
Plan fur Feld Kriegsspiel.Jicin (Gitscin) 1:8000 scale (British Library Maps shelf number 27195 (1). Link to the full catalogue page.
1872. Plan des Schlachtfeldes von Metz fur Das Feld Kriegsspiel.
105 Sections. Scale 1:8000. 105 sections – A2 sheets. (British Library Maps shelf number 33e8). Link to the full catalogue page.
1870. Schlachtfelder bei Metz 1870.
(A collection of 57 orthographic views) (British Library Maps shelf number 24 aa 22). Link to the full catalogue page.
1866. Plan des Schlachtfeldes von Koniggratz.
1: 25,00. 4 sheets. This would be a smaller version of The Konigratz battlefield 1:8000 mentioned in Militar Wochenblatt no. 37, 1869, by v. Troschke. (British Library Maps shelf number 27353 (5). Link to the full catalogue page.
You can begin searching the British library here.