Different answers for you:
Ticketing Systems
I know Service Now and Zendesk are used a lot but SF and Dynamics are also possible for this. All of them have embedded framework capabilities to allow single-pane of glass view and screen pops as well as data dips in Architect to look up for self service.
As for the walk-in, there are a few companies (mostly video-related) that are doing kiosks for walk-up customer interactions with agents.
As for routing of tickets or walk-up sessions, you need to wait for Task Routing or Work Item routing as Genesys calls it so you can route the actual tickets and sessions through to an agent. Currently, we have to use Case-to-Email or Chat-to-Video escalation.
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Robert Wakefield-Carl
TTEC Digital, LLC fka Avtex Solutions, LLC
Contact Center Innovation Architect
https://www.Avtex.comhttps://RobertWC.Blogspot.com------------------------------