Good questions! I've added these to the FAQ:
Q: If I have the $40 early bird version of the $50 tier, does that include the soundtrack?
A: Apologies, but no -- in that instance it's a case of literally being at the $50 mark to get the soundtrack. We should have made the soundtrack at $51 or something, but that just gets confusing. Blah! Again, sorry about that confusion.
Q: How come some same-value tiers have different backer badge levels?
A: That... is completely our bad. It gets really complex to maintain all that, and we slipped up in a couple of places on that in specific. We were focused so hard on making the core meat of it correct that those slipped through.
In all of those instances, you'll actually get the higher backer badge and credits listing, not the lower one noted on the reward tier itself.
On that note: if we ever somehow make that mistake in reverse, we will honor whatever the backer tier says. We'll never downgrade you, we'd only upgrade you to fix our mistake.
Q: How come various backer tiers don't show some of the rewards that they have?
A: For instance:
1. Most tiers $50 and up don't show the soundtrack.
2. Most tiers $25 and up don't show Bionic Dues and Skyward Collapse.
3. Most tiers $35 and up don't show AI War Classic and its expansions.
4. Most tiers $60 and up don't show The Last Federation and its expansions.
Those rewards ARE applied to all tiers at or above the dollar amounts shown there. However, kickstarter doesn't allow for any edits to backer tiers that someone has already chosen, and so we can't edit them to insert these in.
We're talking to them to see if they can do that from their end (I totally see why those should be read-only in case we tried to sneak one past on you taking something out, but in terms of adding new stuff that only adds clarity).
As to the core of the "why," the reason is that these were late additions as rewards we had not planned on offering. We planned out these reward tiers for like a month and a half with the help of our community, and yet even so we've wound up having to make some substantial additions post-launch of the campaign. The good thing is that there isn't anything we regret having added, so it's only been a "wow we regret not having added that sooner, and now it's a bit confusing," which is the better of the two problems we suppose.