This doesn't make sense to me at all.More deadly and not needing retainers is on the DM, not the game.
Needing retainers for <N players can be a function of a ruleset with excess niche protection of N class-linked niches.Hmm. Try Microlite 20. No feats, small abilities list.
Microlite20 Nexus - Home
Microlite20 is a minimalist tabletop role-playing game designed to be usable with the majority of the 3.x OGL/d20 supplements, rules and adventures with little or no advance preparation. The basic rules for character generation, combat, magic and level advancement take up a single sheet of...microlite20.org
More deadly and not needing retainers is on the DM, not the game.
aramis's math notwithstanding, I suspect that in all of the games you mention, the GM is responsible for NPCs attacking PCs. Ergo, each of your examples cease to be deadly when the GM decides that the NPCs are done fighting.This doesn't make sense to me at all. . .
These are all FRPGs that might be played with a small group. They are very different in their deadliness, because of system differences.
Which said math is only about the need for retainers; I should have been more clear.aramis's math notwithstanding, I suspect that in all of the games you mention, the GM is responsible for NPCs attacking PCs. Ergo, each of your examples cease to be deadly when the GM decides that the NPCs are done fighting.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.