Battle Century G has 15 General Skills available for all characters to take. While many RPGs eschew skill lists entirely, most of the games that feature them tend to have 20 or 30 skills in total, so comparatively speaking 15 is a very low number. The system bunches up similar skillsets together so if you take 3 or 4 Skills you already have the theoretical and practical knowledge to cover a lot of situations. Also, many games feature multiple skill training levels. In BCG, either you're trained in a Skill and get an Advantage, or you aren't and don't get it.
In theory, having more skills and variable training levels adds options and differentiates characters more, which would be a good thing. In practice, extensive skill lists have the problem where each one is so narrow that you only care about the most useful one or two for your PC (usually a combat or social skill) and ignore the others unless you have spare points lying around. This is then made worse by having multiple skill levels for them, because you must spend your precious customization points going all in on the good skills instead of wasting your resources on the others. Thus, while I think that games without any skill system are fine, I think having more than 20 skills (not including those that represent psychic powers or the like) is a mistake.
Arguably, the skill system has less ways to represent different levels of expertise and doesn't allow for more specialized builds. The rules approximate this with the use of Traits, resolving the issue. At least in build option terms.
Speaking of builds, how are the Attributes balanced in terms of Skill representation? Well, Fitness and Charm have 8 and 5 General Skills respectively. Willpower and Resources have zero skills both, because they're not supposed to. Awareness has one, because I honestly couldn't justify giving that Skill to a different Attribute (and didn't think of simply not making it a Skill at the time). But wait, what about Intellect? Well, Intellect has a ridiculous total of 12 Skills! The heck happened there!?
You see, most of those are secondary applications of other Skills having to do with theoretical knowledge. So, for example, Combat is a Fitness Skill but military strategy (which is not how you tend to use the skill at all) uses the Intellect stat. The total of Skills where you're expected to actually use Intellect with are just six, which is a lot more reasonable. Still, having so many Skills tied to Intellect means that getting points in Intellect is comparatively cheaper than buying two or three of its Skills, because the stat bonus applies to all of them. To alleviate the issue, most of those Skills have accompanying Traits that require you to be trained in them to use them.
General Skill Review
The structure of the Skill system is fine, but how about the skills themselves? Would the same list be worth reusing in a future project? I'll review the skills based on three criteria:
Proactive - A good Proactive skill is one that can be used to advance the plot or further your PC's agenda.
Adaptable - An Adaptable skill lets you react to GM prompts and resolve the problems they present.
Essential - A truly Essential skill is one where each group needs to have at least one PC trained in it.
If these sound kind of abstract, that's fine. Each entry will have an explanation to make things clearer.
Proactive - Athletics is an alright proactive skill, it lets you get to places most people can't reach. This is a game with giant robots though (or henshin suits or summoned monsters or whatever), so at best this lets you do it earlier than other PCs.
Adaptable - The true power of Athletics is in reacting to things that happen to you like catching a thief or climbing down a building you're trapped in. When the GM puts you in a tough spot, Athletics is the Skill that lets you use your physical prowess to solve the situation and it usually proves its worth.
Essential - While having Athletics is usually a decent idea for your own convenience, most groups will be fine without it by virtue of having mechs. In theory the worst thing that could happen is a TPK when the GM places everyone in lethal peril, but in practice it is probably more like getting captured by antagonists or the such.
Proactive - This is an excellent skill when you have some downtime to use it with, but a terrible one when you're pressed for time. Unless you're playing 24 With Mechs, you'll be able to craft all sorts of cool stuff.
Reactive - Craftsmanship is awful as a reactive skill, it is pretty much its only weakness. I guess you can still use it to try and dismantle a bomb or to fix something broken when in a hurry but just how often does that happen?
Essential - Having someone trained in this is probably a good idea, but you'll be fine if nobody else takes it. It is just so good and does so much that it is unlikely that no one will have it.
Proactive - If you don't mind getting violent or threatening people, Combat is a great skill to help you get what you want when you can't use your robot to do it. You'll run into other people's mechs if you do this often though, so be careful.
Adaptable - Much like Athletics, Combat shows its true worth most of the time when you're in trouble and want to use physical means to solve it. Unlike Athletics, this needs to be a problem you can solve by hitting it until it is not a problem anymore, which is still pretty good even if it is not quite as good.
Essential - When one or more PCs have the combat skill they get to be the ones who show off when the group is in trouble outside of their robots. Depending on how easy or hard it is to get to mecha at a moment's notice, Combat may be essential or just a nice thing to have just in case.
Proactive - Being a good liar can get you far in games if you're not afraid of gray morality in your PCs. Just be careful not to get caught, that's when things get complicated for you (hint: you'll get caught at some point).
Adaptable - With a good Charm score Deception will get you out of a lot of trouble. Arguably the skill is even better used reactively than proactively, because that tends to have lower odds of getting yourself caught.
Essential - Most teams should have someone who can use Deception well, if not both Deception and Diplomacy. While it is not absolutely necessary, it is often invaluable.
Proactive - Saying the right things to the right people can, and often will, be a very efficient way to further your agenda in game. The only downside is that it doesn't work on those not interested in anything you have to say, which hopefully isn't too many folks.
Adaptable - There's a lot of problems you can solve by talking, and those who can't be solved can be often mitigated at the very least. Your own ingenuity at working out a good deal can be more important than dice rolls here, though.
Essential - Just as important as Deception, if not more, because it doesn't tempt fate (read: the GM) to make people figure out they've been fooled.
Proactive - It is solid, but not great, because this is the stuff that good spies are made of. You may need Stealth or Electronics to complement it, but this is almost obligatory for the roguish types.
Adaptable - Reactively, this skill has problems in that it has narrow uses and other skills like Athletics or Combat also use Fitness can achieve similar ends with generally more efficient means. If you're going to train your PC in Finesse, you should be proactive about it.
Essential - As non-essential as it gets. Even if nobody has this, you can get by using the skills mentioned above.
Proactive - I hear hacking is a cool and good thing in science fiction. This is a strong contender for the position of most powerful proactive skill in the game for that alone.
Adaptable - If you can't think of ways to solve most problems using computer skills in a science fiction game, you're not trying hard enough. It might be harder than if you used other skills, but that it is possible (and even plausible) to do so makes the skill very strong reactively.
Essential - At least one person should have this, because you'll need it. If nobody in the team does, then you're probably doing something wrong.
Proactive - As a knowledge skill, Humanities has narrow proactive uses, though it has them and they'll come in handy. Most of those involve research, which needs downtime, so it isn't exactly stellar.
Adaptable - Humanities is useful to figure out bits of lore in the spot, which is okay I guess. It must be something your PC could reasonably be assumed to know though.
Essential - Groups where no one has this are fine. Lore skills are handy to have around though, and it should come in useful a handful of times in most games.
Proactive - You don't need to be playing Mecha Detectives: The Game to want to solve mysteries often in games, making this skill one of the best. That you can use it to find clues in the spot even without the need for downtime makes it even better.
Adaptable - This might be the best reactive skill in the game, because it applies to nearly every reactive uses of Awareness for in addition to all its proactive uses. In retrospect, it probably should have been strictly a proactive skill.
Essential - Every group needs this, period. Preferably in multiples.
Proactive - Not applicable. Well, unless you're going to combine it with Craftsmanship to play mad scientist, I guess.
Adaptable - You use this when someone gets injured or catches a case of plot disease, making it a very reactive skill. It is a strong one though, saving the lives of your fellow PCs (and NPCs too!) is good stuff.
Essential - It is possible nobody in the group will ever need this, but it is still good to have just in case. Sure, you may never need it, but when you do you'll be sorry you don't have anybody trained in Medicine.
Proactive - Catching people's attention and giving good speeches is often helpful but doesn't really do anything by itself. You're either motivating other people or distracting them from something else going on, so this is one of the worst proactive skills there is.
Adaptable - The neat thing about Presence is that it can be a good complement to other people's skills in many, many situations with some creative thinking. It needs the Leadership Trait to be less narrow though, but Leadership is very powerful when you have a good Charm score anyway.
Essential - Probably the least essential skill in the whole game in mechanical terms. Ironically, every team needs a leader and this is the skill that distinguishes an okay leader from a great one, so it balances out to being alright.
Proactive - Another knowledge skill, and like with Humanities it has limited proactive uses. Probably more useful in a science fiction setting than Humanities, though.
Adaptable - The cool thing about an omniscientist PC is that you know about things that you (the Player) would need decades of studying to learn. With Humanities a lot of its reactive uses come down to guesswork, but Sciences is a little more reliable.
Essential - See Humanities, but slightly better because most BCG games will be science fiction. You know how this works.
Proactive - This is a good one, because most games involve some sneaking in or out of places at multiple points. Even without Finesse or Athletics, just being able to move around without being noticed is very handy.
Adaptable - A lot of the time, when you want to hide something in your person or to outright hide yourself from other's eyes, you're doing it as a reaction. The usefulness of both those things makes this a solid reactive skill against many different kinds of shenaniganry the GM could throw your way.
Essential - It is undoubtedly a good idea to have at least one person who can hide from the enemy when the whole of the group is about to be ambushed and captured so they can break the other PCs out. There's even Traits to enable this kind of thing (Smoke Bomb and I was Here all Along) no matter how unlikely or implausible it might seem.
Proactive - There are proactive uses of Survival, but they're not suitable to games involving consistent access to mechs. It is a lot more useful with powered armor and lack of a battleship to ferry you around in between missions though.
Adaptable - If you're separated from the benefits of modern society and any convenient means to get back to it (such as, say, giant robots) then this'll come in handy. This might not happen more than once but, much like with Medicine, you probably want to be prepared.
Essential - Most situations where this skill would help need the session (or the whole game) to revolve around making things different from the norm for BCG. This might just be the least useful skill in the game.
Proactive - Vehicles is so-so, while it can be very useful proactively, because it does what every other physical skill does for a fraction of the cost as a bonus... The problem is that you often don't have access to a vehicle or, more importantly, you have access to your mech which makes Vehicles pointless.
Adaptable - Great if you have your vehicle around when you're being put on the spot, but terrible otherwise. You probably do go everywhere you can with your vehicle though, otherwise what is the point of it?
Essential - As far as skills that every group should have covered go, this is on the worse half of the list. It is useful, but not really essential.
So one thing I notice from going over the General Skills section is that, in trying to make the rules system truly generic, it ended up looking more like something out of a non-mecha game. Many of the example skill checks given aren't related to the kinds of things you would do in the average Battle Century G game, and the issues that many skills have being overshadowed by giant robots have already been noted. With that said, an important part of the system is that you can reskin robots into power armor or magic monsters with minimal tweaking, so this isn't necessarily a bad thing.
One thing I think would have changed is rolling the Finesse skill into Stealth and Athletics. Another would be removing Presence and making a Trait to grab people's attentions once per Episode, kind of like how Leadership needs its own Trait for balance reasons but is probably better off that way. Awareness should have been a proactive skill without being a passive buff to most Awareness Tests as well. Lastly, I would have probably split Craftsmanship into its Fitness, Intellect and Charm versions to keep novelists from being engineers and the such.
Overall though, I'm very happy with the skill system and this skill list, because it makes characters that are capable and powerful from Power Level 1 onwards, as generalists and specialists both.
Next: Superpowers, aka Miracles.