For instance, if I think my game is a cross between Age of Empires and Minesweeper, can I have written on the description of my website "A browser-based hybrid of Age of Empires and Minesweeper" ?
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First up: I am not a lawyer, and the following is not legal advice. For legal advice, you should always consult a lawyer.
Drawing from Examples & Explanations for Intellectual Property by Stephen M. McJohn, there are multiple actions that might be considered infringement of a trademark, including:
...If a consumer sees a mark used in marketing goods or services, she may consider whether the mark owner has authorized the use. If she assumes that every legal use of a mark requires permission of the mark owner, she would likely assume that almost any use of the mark was endorsed by the mark owner.
Initial Interest Confusion
The "initial interest confusion" doctrine finds liability when defendent's use of the mark may attract the attention of potential consumers looking for the products associated with the mark, even though the confusion is dispelled before a sale is made.
Based on this, it's conceivable to me that the IP holder for one of the games you reference could try to sue you for using their trademark without permission, claiming that you are implying an endorsement or exploiting initial interest confusion to promote your game off the value of their IP.
Whether such a lawsuit would actually succeed in court, I cannot say. But it doesn't have to succeed in order to bankrupt you as you try to defend against it.
You could however reference the genres of related games (like "RTS" or "sweeper puzzle"), to attract players searching for similar keywords, without drawing the ire of a specific company's legal department.