If you're looking for some deep and lengthy games to really sink your teeth into, you might be interested to hear that Kingdom Come: Deliverance and Surviving Mars are currently $12 as a part of July's Humble Monthly bundle. There will also be a couple of bonus games released early next month to help spice the deal up, though the above-mentioned games are definitely the highlight of this bundle.
As for whether the games are worth your time and money, I'd say the answer is yes if you're even remotely interested in either one. Kingdom Come: Deliverance may have some flaws due to its mid-budget origins, but it's still a phenomenal RPG and a breath of fresh air in the usually fantasy dominated genre. Surviving Mars on the other hand is a bit more niche as it's a fairly easy city-builder, though it does feature a whole bunch of elements to micromanage and mess around with, so if you don't mind making your own fun, it's well worth checking out.
Before you dive in, it is worth mentioning that the Humble Monthly is a subscription service. As such, if you're only interested in July's offerings and don't really care about what comes next, you might want to unsubscribe as soon as you can. You'll still get Kingdom Come: Deliverance and Surviving Mars and all of the bonus games, so there's really no reason to delay things and potentially forget about it all together.
With that little bit of warning now out of the way, I'll leave you with one of the trailers for Kingdom Come: Deliverance. Have fun!