Is there gonna be a shuttle from the convention center and the They Might Be Giants concert at Bankers Life Field house? 

It's not a far walk

I'm disabled so I need a shuttle or disabled parking at bankers. Still look through Indy's parking info.

No shuttle. It's three blocks from the convention center.

Three Blocks straight down Georgia.   A $5 Cab ride if you really need transport there.

Gen Con really should be providing this info as well.

If all goes well, I'll have an event ending at 7:15 at ICC 120.  Would it be possible to walk to the Banker's Left Field House in 45 minutes, or would that be cutting it too close?  Also, will we be able to bring bags to the concert, and if not, will there be a place to stow them anywhere (paid lockers or etc)?

45 minutes from the ICC to the Fieldhouse? I'd be in shock if that walk took more than 15. 

No idea about the bags thing, though. Sorry. 

Thanks!  Although the bags thing may turn out to be a big deal...  Anyone else know about this?  I'm imagining myself trying to get into the concert with a messenger bag full of books and purchases, and getting turned away.  Surely others will have the same issue.

The Fieldhouse is three blocks from the ICC. As aldctjoc mentioned, you should have plenty of time.

Here is their bag policy:
"Backpacks and any bag larger than 14”x14”x6” will not be allowed. Single compartment sling bags, or similar, as well as diaper bags will be permitted as long as they are smaller than 14”x14”x6”. All guests entering the Fieldhouse are subject to security screening, visual inspection, and bag inspection conducted by Bankers Life Fieldhouse personnel."

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Alec Usticke, Unofficial Gen Con Indy Facebook Discussion Group