Well, the obvious fantasy ruleset for 10mm is Warmaster, and that was very simple:
- All non-cavalry units are on 40mm wide x 20mm bases
- All cavalry units and chariots are on 20mm wide x 40mm long bases
- All warmachines and artillery are on 20mm wide x 40mm long bases
- Monsters and such (with or without riders/crew) are on 20mm wide x 40mm long bases
- Heroes are on 25mm round bases
Then there are rulesets which despite having some detail, are still abstract enough for 10mm. My example here is Kings of War.
Basing is very similar to Warmaster, but some sizes and some orientations are a little different, especially when "translating" down to 10mm. Here's what I'm doing:
- All regular-sized troop units are on 40mm wide x 20mm bases
- All above-regular sized troop units are on 50mm wide x 25mm bases
- All cavalry units are on 50mm wide x 25mm bases
- All monstrous/large infantry units are on 50mm wide x 25mm bases
- All chariots are on 20mm wide x 40mm long bases
- All warmachines are on 20mm wide x 40mm long bases (unless they fit comfortably on 20mm x 20mm bases)
- Monsters and such (with or without riders/crew) are on 20mm wide x 40mm long bases (unless they need a bigger base, or else fit comfortably on 20mm x 20mm bases)
- Single heroes on foot are on 15mm x 15mm bases
- Single mounted heroes are on 15mm wide x 20mm bases
- Single monstrous/large infantry heroes are on 20mm x 20mm bases
However, as long as both sides are the same, Kings of War
can be played using the Warmaster basing conventions. I would suggest that a few bases of additional cavalry are based "wide" for each faction however, for when you run small harassing units of them, but otherwise small differences are easy easy enough to hand-wave away if all players are on the same footing.
Lastly, if you really want the most flexibility, I would perhaps consider using some metal or magnetised plastic trays or similar, and using smaller bases on them to make up bigger units - the tray keeping them all together when you move them about. I'm not suggesting anything ridiculous here, but 20mm x 40mm, 20mm x 20mm, and 40mm x 20mm are all common enough and can be arranged to make 40mm x 40mm, 60mm x 40mm, or whatever other sizes you need.
For those rare games where equipment or such matters broadly, you can even use a mix of similar models with different weapons, putting the "correct" ones at the front, and filling in behind with others. So a 40mm x 40mm Orc unit with spears could have a 40mm x 20mm base of spear-armed models in front, and a 40mm x 20mm base of sword-armed models behind for example.
Anyway, these are just my thoughts; apologies for how long-winded this post ended up being, but I guess basing is just one of those things that seems to change from game to game on whim!
