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Featured deep discounts: https://store.steampowered.com/sale/special_deals
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Get free stickers by completing your discovery queue: https://store.steampowered.com/explore
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Steamdb: https://steamdb.info/sales/
https://store.steampowered.com/recommender
It's under "Reccomendations" > "interactive recommender" in the main store menus.
Besides changing the popularity and age weights as shown above, you can click on a game on the sidebar to exclude its playtime from influencing these recommendations.