OMNIS is a game about the ground you're currently standing on. You plant something (a Spore, say, or eventually a Unicorn, because the game stops pretending to be realistic fairly quickly) on a real GPS coordinate. It grows there. Not metaphorically: on a timer, in real hours, while you do something else entirely.
Later, you walk back. If it's still there, you harvest it for XP and Essence. If someone else found it first, they harvest it instead, and you get nothing but the walk. That tension, is it still mine, is it worth going back for, is most of the game.
Other players' structures are visible too, and you can help them along: boosting a stranger's planting speeds its growth and permanently raises what it pays out, in exchange for a currency called Karma that gates the game's later structures. Generosity, in other words, is load-bearing.
There is a levelling system, a research tree, a prestige mechanic called Rebirth that resets your progress in exchange for a permanent bonus, and eventually a Home base you can plant a whole region from without leaving the couch. None of it is explained here. It's explained on the About page, at whatever length you can tolerate.