This looks great! For tilesets you can find lots of free ones on the RPG maker forums. For example here's a big list of tilesets with a modern/futuristic setting: https://forums.rpgmakerweb.com/index.php?threads/grannys-lists-modern-and-futuristic-resources.9843/
If you have any specific questions about RPG maker let us know and we'll try our best to help.