I'll say it again: keep pestering the Humble people!! We'd love to be part of the next Bundle and we'll put in some cool extras. We just need to convince them.
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I suspect they are reluctant because they don't want to release a dedicated RPG humble bundle because they think it would flop and tarnish their brand.
Which I think is BS.
I don't think an RPG bundle would sell the 2 million dollars worth that Humble Bundle 3 did, but it would certainly do as well as the (rather lackluster, in my estimation) Frozenbyte bundle they did.
But even if they don't want to sell an RPG dedicated bundle, I don't see why they wouldn't want to include 1 RPG game in one of their usual bundles.
Who, for example, bought Humble Bundle 3 just to get Cogs? Cogs is a really kind of a boring and imaginatively uninspired game. I had never even heard of it before Humble Bundle 3 and after playing it I immediately forgot it. So I can't imagine that including Eschalon 1 (or something from Spiderweb games, to name another indie RPG example) would be any worse for them than including something like Cogs. I actually think more people would get excited by the inclusion of an RPG just because it would demonstrate greater genre diversity and reach out to a much larger demographic of customers.
Plus, if they are really dedicated to indie gaming it kind of goes against their stated purpose to not include an RPG. Heck, Spiderweb games practically invented independent gaming before indie games were even cool. So it sucks that they refuse to recognize indie RPGs.