Or games which have been released as part of a long-running series, which is what my two examples are.
Civilization. Yes, I got Civ IV, and played it to death for like a month. But eventually, despite all the new bells and whistles, and despite the devs fixing Infinite City Sprawl (which really soured me on III), it’s at its core still essentially the same old Civ-same old combat system, same basic strategy, same tech system (in general), same cheating AI (at higher levels), same middle game ennui. Haven’t played it in about a year-took a brief look at the expansions, didn’t spring for them.
Heroes of Might and Magic. Number III all told was the best of the series, but when I broke down and got V a few months back, the same syndrome above arose. The new skill system was terrific, and the 3D graphics were pretty cool, but it’s still the same old Heroes. Combat system had a few new wrinkles (like how initiative worked), but we still have the old 2D battleboard which dates back to the original King’s Bounty. Spells-only a few novel incantations, still had Mass Slow, Armageddon, etc. AI was annoying and made for boring games because it invariably kept trying to invade you relentlessly until you invaded it and finished it off-since I like to explore away from my home base that was hugely peeving.
You see the designers of games for such long-running series are between a rock and a hard place: if they try to innovate like crazy they risk pissing off their core fanbase, which is precisely what happened to Heroes IV. As an effort, IV was a noble experiment; as a game, a quirky failure, with severe balance issues and brain-dead AI. Reinventing the wheel like that always entails risks as you push the envelope beyond the tried-and-true, only to find that your innovative game system completely lacks balance or gameplay.
If on the other hand they stick with what worked over the previous X iterations, even the most hard-core player will get bored with it eventually. In my ideal world the next Heroes game will have fully 3D battlefields, where if you have 10 dragons in your army you will see 10 dragons on the battlefield, and get to watch them as they swoop down upon a pack of hapless orcs and fry them. A overhauled and dynamic spell system and skill system. But I understand the risks with going that route.