Metal Slug Infinity, Ekkorr's idler which was announced in October of 2018, is now available for pre-registration on the Play store.
SNK licensed Metal Slug to a Korean developer, Ekkorr, which found success with its idler Endless Frontier Saga 2. So it’s not a surprise that Metal Slug will be taking the same route and be an idler, where you focus on micro-managing rather than the action.
The game will most probably be free-to-play on release and it will definitely include in-app purchases. The exact prices for the IAPs are not listed, but advertisements are guaranteed to appear as well.
Design-wise, it has recognizable units, but a completely different style. They are trying to attract new players, rather than the already existing fans of Metal Slug.
It is a questionable decision to license such a nostalgic game only for it to be turned into an idler. Time will tell how successful it will be.
If you wish to pre-register, you can do so on the Play Store.