Also, are upgrades restricted by the original game’s software architecture or licensing agreements with developers?
I would think so. Game providers own the games, the casinos cannot make changes that is not allowed or permitted by the providers.
- Jay -
Nowadays we see more and more casinos developing their own slot games, which they will label and make known to players. For such games they can easily upgrade and make any changes they want, but for the ones for which they partner with providers, they don't have access to making such upgrades; it will be up to the provider to check the people's demand and make changes based on the request.