First we need to sort out different things we are talking about.
1. How does "radius" affect melee combat
2. How does "radius" affect missile defense
3. Can we use this attribute to make gameplay better?
4. Can we use this attribute to simulate Ifikratean-style phalanx better?
Ad. 1)
a) Smaller radius does affect spacing of soldiers during melee AND WITH GUARD MODE OFF. Classicals hoplites with radius of 0.2 will not spread out during the fight. They will still envelop the enemy if given a chance and won`t have stupid problems with facing (common thing with guard on). However by staying close together they will hold formation better, than with the default radius. In general they will fight better and very much phalanx-like without the need to use guard mode. To do: test how much better will they fight.
b) Units with loose formation, like peltastai, if given 0.2 radius will do the same as hoplites. If they enter the fight, they will get close together and present a solid shieldwall to the enemy. They will keep their loose formation in guard mode though. This is definately not something we would like to see in the game.
Ad 2)
When I`ve done the tests earlier on, I got the impression, that units with small radius were more resistant to missile fire. But now after 2 custom battles I`m not so sure. This needs further testing.
Ad 3)
Radius attribute is something to consider for close order units, primarily classical hoplites. However we must ask ourselves, are they not good enough already (using the guard mode of course)? By giving them small radius we will prohibit them form using loose formation in combat (they will stick together in combat despite being in loose formation). And we will make them stronger overall.
Another thing, which needs testing is whether small radius will give units undeserved resistance to missiles. As already pointed out, we cant give small radius to all the units and it would be unfair if just some of them had "unnatural" resistance vs. missiles.
Ad 4)
If we are going to use (small) radius attribute, than definately classical hoplites, german warbands and other units fighting in a shieldwall-like formation should receive it too, besides the Ifikrateans (do we even have accounts of them fighting in a particularly close order?). That means, playing with radius attribute will do zilch to increase Ifikrateans performance in comparison to their more ancient brethren...
Other possibility is to give small radius to the traditional hoplites and leave Ifikrateans as is - they will be still able to hold close formation (with guard on) but unlike hoplites, will able to spread out too (to not get outflanked for example).
Bookmarks