Out of all the cards in System Gateway, it's Regolith Mining License that has impressed me the most. It feels unbeatable when I play with it, and (from the Runner side) unbeatable when I play against it. It doesn't go into every deck, but it makes the decks that it does go into a lot stronger.
There are three main things that can happen to a Regolith Mining License. Let's look at them in turn.
Case 1: The Runner doesn't trash it
First, let's look at what happens when it doesn't get trashed – in this case, the numbers look absolutely amazing. You end up spending six clicks (one install, five paid ability) to gain a profit of 13. That's slightly better than 2 per click, if compared naively. When comparing different economy cards, I like to add in the cost of drawing the card (for most non-HB Corp decks, a card is worth about 1 click), so the actual rate is slightly worse than 2 per click, the way I compare things. Either way, though, this is a ridiculous rate of economy, and blows most other Corp economy cards out of the water (2 per click is a premium economy rate for Runner credit economy, which is better over large timescales).
If we're looking for comparisons, we're looking at the Hedge Fund (4 over 1 card + 1 click = 2/click) level of quality to see what might compete with this card, in a deck that can protect it. But this card has much more impact per card slot on your economy than Hedge Fund does. The thing is, Corps are typically incredibly tight on deck slots; if you run three copies of Hedge Fund, you're only going to get 12 of revenue from them (over 3 cards + 3 clicks), so your super-efficient economy won't get you that far and you need to find other cards to supplement them. If you run one copy of Regolith Mining License, however, you're going to get 13 of revenue from it (over 1 card + 6 clicks), a very similar amount – and that's just one copy! So with multiple copies of the License, your economy can have huge longevity, in that when you come to a quiet moment where you want to spend clicks gathering credits, you can make use of all those clicks to gain credits efficiently rather than having to spend some of them using the least efficient basic action in the game.
Case 2: The Runner runs it while it's installed in its server
So things look pretty good so far: if the Runner doesn't interfere, the numbers on this card are favourable to just about anything else. But what if the Runner does interfere? The gain you get from that is going to be somewhat dependent on your deck (which is why you can't play this card just anywhere). The thing is, you can put assets into any remote server that happens to be empty; and if your top priority as the Corp right now is fixing your economy (say you just scored an agenda, or rezzed a large piece of ICE, and are trying to recover from the economic hit), you probably aren't going to be busy trying to score an agenda while you're doing that. So Regolith Mining License is, in practice, a card that you put into your scoring server for a couple of turns – that means that contesting an installed License is, in practice, going to have a similar difficulty to contesting a scoring server. Runners have a lot of ways into scoring servers, but they tend to be very expensive or limited in use: as the Corp, you generally love it if a Runner spends a lot of effort getting into your scoring server and doesn't even gain any agenda points as a consequence (and even has to pay an additional 3 to trash the asset when they're done). So if you get as far as installing the License, you're generally going to profit regardless.
A good comparison in this situation is NGO Front, which is generally regarded as a very good card (and widely played). NGO Front is basically a bait card (that can be used to trick the Runner into running an expensive server), that also gives you some moderately efficient economy in the process (and thus means that if the Runner doesn't take the bait, you still benefit). Regolith Mining License is bait in a different form: if you rez it to take the credits, the Runner will know it's there, but given how much economy you'll get if they don't run it, they may end up deciding it's better to run it anyway. So as long as you have an appropriate scoring server for the stage of the game you're at (which could be anything from a Vanilla on turn 2 that makes the runner spend an Inside Job or Boomerang, to a fully rezzed glacier on turn 20 that eats up much of the Runner's economy), your License will be giving you huge benefits if the Runner does decide to run over and trash it, too.
Another good comparison is Daily Quest, which I reviewed last year, and concluded that the best use of a Daily Quest was as something to put in your scoring server for a few turns while you weren't using it for anything else. Regolith Mining License serves a very similar role, but is much burstier; if you only have a couple of turns free, it'll give you a much larger profit. Daily Quest can be better, because it's clickless, and thus it'll give you a larger gain if you had some better use for those clicks. But Regolith Mining License is powerful because its click-intensive play pattern is pretty much exactly what most decks are looking for when they're low on credits; you can't do very much when you're poor (e.g. as the Corp, clicking to draw cards rather than to gain credits is generally only going to make matters worse), so you would want to be spending as many clicks as possible getting your economy back up to a workable state anyway.
One other point to mention is the click timing for installing and using your License. There are two main ways to use it: either you install it click 1, rez it, then click it for credits twice; or else you install it, leave it unrezzed overnight, and click it three times the next turn. The former pattern gives you 4 for immediately (the same amount as a basic Cyberdex Sandbox turn, which is something that Corps are frequently willing to use in practice when low on credits); you have to spend a card, but the Runner then has to spend , 3 when they run over to trash the card (plus whatever resources it costs them to get into the server, which may be a lot more). So this is the safest option when you're critically low on credits. I actually prefer the "leave installed overnight" play, though; generally speaking it's better to use this one when baiting the Runner into running the unrezzed asset is your preferred option (i.e. if you wouldn't lose much if the License gets trashed), because it gives less information to the Runner (and if the Runner chooses not to run it, it will become even less worthwhile running the next turn when you take more than half the credits).
So if the Runner doesn't trash the License, it's great all around. If you install it and the Runner decides to go trash it, the benefits depend on the sort of deck you're playing; they won't be worth it in a shell game deck, or in a rush deck that uses an agenda economy (and wants to keep its scoring server consistently occupied), but if you have a traditional sort of scoring server this case can be even more beneficial than the previous case. (Bear in mind that even if your deck normally has a decent scoring server, it may not do so if it stumbles in the early stages of the game, e.g. if you don't draw enough ICE or are agenda flooded. But this isn't really a mark against Regolith Mining License because there's very little a purely economic card can do to help in this situation anyway.)
In short: if we have the right sort of deck, both these cases are amazing. What does the fail case look like?
Case 3: The Runner randomly accesses it in HQ or R&D
This is the worst of the three cases, but it really isn't all that bad. If the Runner was spending a click (and probably icebreaker costs too) looking for agendas, and found a Regolith Mining License instead, it's usually in their interest to pay the 3 extra to trash it (because they've already incurred a significant sunk cost). This case is shared with several other economy cards; Mumba Temple is a good example to look at. Mumba Temple is good enough to have been MWL'd for ages, and a significant part of its strength is the fact that the "it gets trashed for 3" fail case really isn't that bad. An unexpected 3 payment is just large enough to be annoying, and the only hit to the Corp is that it makes it harder for them to draw into economy cards because some of them have been trashed from the deck, and that the Runner gets to see a different card if they run the same central again.
So this is a situation where the card is notably worse than a Hedge Fund: you're making R&D more porous and giving the Runner the option to interfere with your economy. (One feature of Hedge Fund that's hardly ever mentioned is that it blocks repeated R&D runs by being untrashable, but this is actually a significant factor in what makes it such a good card; frequently the fact that it's untrashable has a larger impact on the game than the 4.) But again, whether this is a major drawback or an irrelevant nuisance will depend on your deck. If you're playing glacier, you probably won't be facing many random single accesses on R&D or HQ (Runners will prefer to use big multi-accesses against glacier if they have them available), so the drawback doesn't come up very often. However, some rush decks can easily go the whole game without ICE on R&D, and Regolith Mining License is not going to be a good basis for the economy there.
Regolith Mining License is a really, really powerful economy card in the right deck. Like most assets, it gives the Runner options (trash it, or leave it?), and giving your opponent options is something that tends to make a card weaker; but the benefit if the Runner chooses to leave it is really large, and if your deck uses a scoring server to score its agendas, the benefit if the Runner chooses to trash it can easily be even larger. It does have a downside (including it in your deck makes R&D a bit more porous), but if you have the sort of deck that naturally wants to protects the centrals in addition to a scoring server, it's not much of a downside. The card will, however, fall flat if you're playing a deck which has no real scoring server (e.g. if you're scoring from hand with Biotic Labor), if your deck relies on "winning quickly" as its primary form of central defence, or if your deck is designed to chain agendas with no downtime between them (in such a situation you should probably be running an agenda economy instead). Even in today's lightning-fast metagame, though, there are still decks around that either can afford to, or else sometimes need to, take a break from the scoring for a couple of turns to get their economy back in order.
The real reason it's so powerful, though, is when it comes to deck construction. In an appropriate deck, Regolith Mining License gives you a huge amount of benefit for a very small number of card slots, meaning that you have that much more room to pack your deck full of cards that do whatever it is your deck is doing rather than needing to dedicate slots for economy. (Note that it won't handle all your economic needs entirely by itself; this is mostly because with only 3 copies playable, there's no guarantee that you'll draw one at an appropriate time. But it'll help reduce the number of deck slots you need to spend on creating a functional economy.) It even has an influence cost of 0!
One thing to help contextualize how good Regolith is that if you use the "overnight" option of three clicks in one turn, you are getting Melange Mining Corp value, and you have two uses left over. It also costs two more to trash than Melange as well. So clearly an improvement over some former Corp asset economy.— dnddmdb
This review was very helpful, thanks. When I saw serious players using Regolith in CTM I suspected Regolith was for real.— superheronation