GameMaker is active. It's constantly updated. Even if the original software is old, the current engine is much more recent than RMXP (which hasn't been supported since VX was released, I think).
But GameMaker is a totally different thing. RM is much simpler, which makes it a good candidate for people who want to tell stories, but don't want to learn how to code or create complex gameplay mechanics.
Unity is a more complex engine that allows you to make basically any type of game you want. Even AAA stuff (good luck with that though

). It's also free, but it takes quite a bit of effort to get the hang of it, from what I heard. Not for casuals.