cmaggard is being downvoted, but he's quite right. Playing Worms means repeated multiplayer matches on a handful of maps, with a couple dozen weapons that don't change. Sequels repeated most of the maps and weapons and added a few more, and these would indeed be small IAP or perhaps $5-10 DLC on Steam if made today. I think it's fair to say that the sequels were more derivative than the sequels of most other franchises since at least those franchises could add new campaigns (Worms added a campaign-esque experience at some point that was mainly a chain of single-player matches) or do significant graphics updates (which Worms could not meaningfully do since its cartoon graphics and physics were good enough early on in the series.)