What distro were/are you using?
Ubuntu 12.04 x64 LTS w/ Gnome Shell
Linux keynote 3.5.7-030507-generic #201210130556 SMP Sat Oct 13 09:57:36 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
A bunch of additional packages were installed and removed occasionally in the past but libcurl3:i386 was absent all the time.
The issue is that the game includes libcurl.so in the lib directory, but not a libcurl.so.4 symlink. For now, creating the symlink yourself will work around the issue (cd lib && ln -s libcurl.so libcurl.so.4).
Ok, @thestinger, apt-get-removed libcurl3:i386 and tried it the way you suggested. Works fine!
This bug was closed because the issue concerns the game and not the Steam client. Please contact the game developer on their official website with this information.
I just tried the workaround myself and it didn't work for some reason.
I had Steam grab this game for the first time in response to @MrSchism, the game runs on Gentoo 64bit with no additions to my system. ldd reveals swordandsworcery_pc links to libcurl.so.4 => /usr/lib32/libcurl.so.4 and /usr/lib32/libcurl.so.4 is a symlink to /usr/lib32/libcurl.so.4.2.0.
Also, LD_DEBUG tells us it is trying /.local/share/Steam/SteamApps/common/Superbrothers Sword & Sworcery EP/lib/libcurl.so.4 first and fails on my system, but eventually gets a hit on /usr/lib32/libcurl.so.4.
Edit: Removed inaccurate line.
I wasn't paying attention and downloaded a wrong version. Fixed that and restarted the Steam client.
Nothing extracted yet.
(1) Claimed humble indie bundle #6 steam key unlocking "Superbrothers: Sword and Sworcery EP".
(2) Installed it successfully.
(3) Failed to launch for the first time.
(4) Retried with console output, got that:
(5) Installed
libcurl3:i368with:(6) Finally the game launches successfully.