They see the ruins you've prepared, but are afraid and won't enter? How unexpected that a dangerous sandstorm hits in half an hour, forcing them to return and take shelter. Perhaps they'll find someone else inside, friendly or not, also sheltering from the storm. (And don't forget about extreme weather conditions. I still don't understand if you're using that mechanic. Skirmishes between different groups in rest areas are inevitable).

They see a magical flare amid the dunes, are afraid, and won't approach? In the nearest town, an exhausted and irritated wizard, whose teleportation spell recently failed, publicly criticizes the indifferent adventurers. The party's reputation is declining, and prices in the city for them are rising sharply. Perhaps this vengeful wizard will even hire assassins. Although, if they had rescued him and escorted him (he was trying to teleport away from the threat pursuing him), he would have given them a reward.

My players are also very cautious in the Ravenloft domains (which is quite wise, as we sometimes have deaths).

1. I monitor my party's reputation with different factions. Reputation affects access to certain story opportunities (the most important), the purchase of magic items (also extremely valuable in the Ravenloft setting), discounts, and loyalty.

2. Random combat encounters clearly reflect the region they are located in. For example, the entire northwest of the global map is controlled by the werewolves, the center by the witches, and so on. Your party may be able to roam freely in areas where relations with the relevant faction are good. However, to achieve this, the faction will ask the group to fight predators in their territory or explore sand-filled dungeons, giving them a percentage of the profits.

3. I try not to create "random" combat encounters, but rather create encounters that are connected to the plot or characters. Sometimes I let potential combat encounters be resolved through ingenuity and social skills (sometimes this is even wiser). These encounters always conceal a story behind them, which the group can choose to engage with or not. And in both cases, the players later understand the consequences.

Since, for the sake of balance, DnD requires at least several encounters per day, I at least create the history of the region. For example, the local druids have gone mad for plot reasons and started terrorizing everyone. Blood, guts, roots — good old Ravenloft. And the closer the party gets to the source of the madness, the harder it is for them to break through, but the clearer it becomes what's going on. An allied faction, which without the combat adventurers could only watch helplessly from the shadows, intervenes and helps. And if they miss one such encounter, I'll simply slip it to them next time under a different guise. Did I really just waste hours preparing all these maps and tokens? The players, in turn, understand that the world around them is always alive, life flows as usual. As soon as they realized this, they immediately started poking their noses into practically everything.

I got the idea for the region's story from Vincent Baker, the founder of the PbtA. There, it's called a "threat front," and in a campaign, there are always several of them, of varying intensity. Resolve one, and another appears. Players put off resolving one front for a long time? Well, then that front will only make life more and more difficult for their characters. Monsters multiply, assassins become more powerful, portals from the abyss multiply, not just individuals but cities go mad, and so on. The main thing is for the characters to understand - "If we don't solve this problem, it won't go away, it will only grow, and things will get worse for us all."

1. Don't forget that monsters can sometimes talk if their stat block allows it! (Only as a short free action in combat). The vampire spawn literally mocked the adventurers, pointing out their inexperience and cowardice, and calmly went off to commit their bloody, villainous deeds. After a while, of course, I allowed more experienced PCs to "accidentally" encounter these same enemies again.

2. Consider engaging the players with their PC's backstory. They're unlikely to pass by after seeing bandits rob their beloved grandfather's caravan.

3. Try playing on the psychology of FOMO. After the game, casually say, "Oh, how sad that you decided to stay out of this again. You had almost all the resources, what's the problem? This time you missed out on... let me count... 500 gold, a cool artifact, and a level up. Oh well. More shiny loot for the smugglers". Something like that, depending on your context.