I haven't played (much) of 3 & 4 for the sole reason that those games (purportedly?) do require at least some knowledge of the Japanese language. The worst part is supposed to be a robot boss in the fourth game that asks you questions which you have to answer correctly in order to do damage to him (clicking through a video, I would imagine it's
this one). I'm also not inordinately keen that both games seem to incorporate a lot more of these gimmick set-pieces, namely with the giant robots, those are just awkward as all hell. Lastly, it seems like 3 is by far the longest game in the series, mayhap the veridical attempt at crafting a true "Super Goemon World", thus concluding ambitions which were already burgeoning in 2.
2 fortunately can be played with almost no verbal interaction whatsoever. There is one item you're required to buy (a pass) which is simply done by walking into a shop, selecting said item and picking the first option. To save the game, you look for the house with red curtains in a town, select the right-most option and then the first one. That's all you have to know about the language. Of course, it's most likely that you miss out on several secrets/additional amenities (such as extra lives), you can definitely beat the game without those, though. And while I'm at it, I might as well explain the controls of the often-mentioned robot fights:
Y: Jab
B: Punch
X: Bomb (must have gotten one/two in the stage beforehand)
A: Bullets (consume money)
L/R: Guard
The jab is almost entirely useless, a veritable beginner's trap. You want to use the punch to do some respectable damage to bosses and push them back. Depending on how well you do in the genocidal godzilla simulator stage leading up to the battle itself, you have more health, money and, most importantly, up to two bombs (dropped at specific thresholds of energy). Using a bomb will automatically (at least I think it does, I've never seen it miss) hit the boss and reduce its health by 50. Some attacks you can intercept by a well-timed punch of your own, some of them you have to block with the guard command first, archetypical trial & error. The congruence between where your reticle is and what you're actually going to hit is not horribly satisfying, either.
The stages themselves are self-explanatory. There is a single stage with a fake exit that will fool you the first time yet is obvious to figure out afterwards. As I've mentioned, lots of instant death trap which are difficult to avoid without prescience, but also mostly unproblematic after a few attempts at most. There are some seriously tricky jumps where you have to land on rather rapidly moving pendulums, those require some timing and are some of the best parts of the game in my opinion.
You probably want to play as the ninja character (on the far right of the selection screen) for his movement speed and great jumping capabilities. He also gains the ability to throw his kunai once he is powered up which is of course extremely useful. His only problem is the final boss although the speedrun I've posted above doesn't transport this whatsoever, it's possibly just me not getting a good grasp on the patterns. Goemon is also a consistently good character to use, Ebisumaru only really shines against the final boss on the other hand.
Having said all that, I would just recommend playing the first SFC game (which is rich of me to say in light of the fact that I'm only familiar with those two!
) in its translated form. I understand why delicate linguists among video game enthusiasts reprimand the translation since it is not what you would call chatoyant prose begotten in an entheal phrontistery, it serves its purposes entirely on a functional level nonetheless. You have to buy a few more items and find hidden passageways and such than in the first game, it doesn't feel like RPG detraction or filler whatsoever, though, and more like judicious resource management. Unlike the second game, where townspeople will toil a halcyon, irenical life, everyone is out to murder you in the first game, starting with the initial screen. That is, all but the women, hitting them will penalize you in the form of subtracted money. I find this to be an ingenious little detail for you are always tense considering the ceaseless spawning of vile peasants, this will force you to react quickly instead of continuously mashing.
Health extensions are not permanent unlike the second game, they only last for one entire level (which usually consists of two sub-stages, the overworld and the dungeon part) which is again a moreso arcade-like structure. Your weapon upgrades not once, but twice, and there is an interesting balance between the longer pipe and the yoyo, the difference between your regular attack and tossing coins is likewise carefully construed. Stages revolve around you being able to fend off relentless enemies whilst also doing lots of creative platforming where the second game is more about memorization and handling specific stage hazards. Bosses are not unduly threatening in this game either, a lot more respectable than those in 2 all the same.
I will say that you have to get used to the timing of Goemon's attacks as well as some of the more pronounced foibles regarding a few hitboxes (particularly during the overworld view). And while I respect that getting hit will power you down, I don't think it was wise to have such a horrendous default walking speed during the towns sections (get yourself as many sandals as money can buy as soon as possible!). Outside of that, I think this is a stellar game for enthusiasts of our proclivity. I've seen a lot of critiques towards the first game when it comes to the overall SFC series, calling it "needlessly difficult" or "hardcore", I call it incorruptible game design. It places gameplay first and then builds marvelous presentation around it as it should be the case. I get the distinct impression that later games - while still remarkably solid - start to dissipate that line, being content with delivering ocular wonderment first and coterminous gameplay second.