what's an Irem game you really love? i feel like that studio is a bit of a blind spot for me
Great question! Irem is actually a company that I'd like to dig into deeper myself (I've only ever played R-Type I and II within that series and that's probably their most well known one), but here are a few of their games that I've really liked. You only asked for one, but hey, why not throw in some extras, right?
Atomic Punk
This one might be cheating because it's just Bomberman, but Irem actually made two Bomberman games for the arcade that have quite a different visual style compared to the regular games. The Bombermen kinda look like football players and the visuals bring something like a carnival or show to mind. The gameplay is faster than usual and makes some really interesting tweaks to suit the arcade format, such as resetting your power levels each stage so you have to scramble at the start of each level, and introducing an AI bomber in every level that has the same abilities you do. It also has four player co-op! The sequel is similar but doesn't feel as balanced or as interesting, so I'd recommend this one over that.
Ninja Baseball Bat Man
This one has definitely gotten more of a following in recent years, and for good reason. I remember playing it years ago on one of my "try random games on MAME" binges and I was blown away by how great it was despite the silly premise. It has gorgeous visuals with large sprites and levels full of weird baseball-based enemies and other freaks, the animations are great and each character gets a load of unique ones, and the combat feels fast and fun thanks to a simple combo system that strikes a nice balance between flash and substance. Even if you play the big slow guys like I tend to, this game never feels slow. It's not hard to figure out, but each character gets a surprising number of moves too! Also, it's one of those games that takes place in real world locations (America in this case) so it's fun to see the wildly unusual interpretations of each location from a Japanese perspective. This is one of those games that feels like a passion project through and through.
Kid Niki: Radical Ninja
This is something of a "nostalgia pick" for me because I've had the NES cart for years and would always pop it in to try and get a little further. I also have the actual arcade machine chilling in my basement that I've been meaning to fix up into a more playable state for years, so the little guy kind of ended up in my every day life in more ways than one! It's a very simple platformer with an interesting choice of weaponry (he's got this weird spinning blade thing that he twirls in front of him), some charming aesthetic choices and a bizarre "80s surfer dude lingo" vibe if you're playing the English NES version. By all accounts, it's a pretty basic but deceptively challenging platformer with an incredibly peppy soundtrack that's still engraved upon my soul to this day. If it interests you, Irem's Hammering Harry/Daiku no Gen-san games are pretty similar platformers that hide harsh difficulty beneath their cute exteriors, so I'd recommend those too.