This is definitely an interesting UX puzzle to solve from a game design perspective. I get what you're saying on finding the right balance.
Beyond sound alerts, some glow effect around an object might help? A tutorial at the start almost seems necessary so people get the mechanics, if you don't have that already. Just my $.02!
Beyond sound alerts, some glow effect around an object might help? A tutorial at the start almost seems necessary so people get the mechanics, if you don't have that already. Just my $.02!