The 1942 series is a series of arcade vertical-scrolling Shoot Em Ups developed by Capcom, set mainly in World War II. The player is an American "Super Ace" in a P-38 Lightning who spends a surprising amount of time kicking the spit out of the Japanese Navy for a series made in Japan.
1942 (Arcade, 1984)
1943: The Battle of Midway (Arcade, 1987)
1943 Kai (Arcade, 1988)
1944: The Battle of Midway (Famicom, 1988) — A limited release version of 1943 that featured an extra weaponnote a powerful laser shot represented by a "cat" sprite, of all things for the P-38 and nothing else
1941: Counter Attack (Arcade, 1990)
19XX: The War Against Destiny (Arcade, 1996)
1944: The Loop Master (Arcade, 2000; developed by 8ing / Raizing)
Attack Its Weak Point: In 1943, the Ayako bombers can only be damaged in their engines, but you can keep shooting the same engines even after they have been set on fire. They are defeated once all their engines go down.
Critical Annoyance — In 1943 and 1941, an alarm goes off whenever your health runs low. The NES port of 1943 is worse: it replaces the current BGM with a Jaws-like tune when your health falls below 20.
Damage Is Fire: The Ayako bombers show their damage level by how many engines are on fire. Ayako I's engines catch fire in pairs, Ayako II's engines catch fire as such: First, second, and 3rd/4th together, Ayako III's engines catch fire one at a time.
Kaizo Trap — In 1943, most ship bosses will explode into shrapnel when defeated. Better avoid it, especially if you manage to beat the final boss and forget all about the shrapnel...or you can shoot it for extra points.
Life Meter — Varies. In 1943, you get a Life Meter that drains over time (though you can't die of time drain). 1941 offers Hit Points that you lose one of with each hit. 1944's and Joint Strike's are more similar-looking to 1943's, without the time drain.
Sequel Escalation — Inverted and played straight at the same time; up to 19XX, each game has less levels (1942's 32 stages -> 1943's 16 stages -> 1941's 6 stages), but each newer game has stages that are more varied and have more complex gameplay than "fight waves of enemies in the sky until you reach the next end-of-stage carrier."
Shown Their Work — The Japanese versions of 1943 featured accurately modeled (as accurate as a Famicom could, anyway) versions of actual WWII IJN capital ships. A diligent player could recognize many Japanese battleships & carriers including the Ise, Nagato, Yamato (post refit), Akagi, Hiryu, and several others.
Smart Bomb — 1943 and 1941 have special attacks that damage everything on-screen at the expense of health. 19XX and 1944 instead give you bomb items, with the former allowing you to charge up a bomb attack that deals more damage than simply tapping the bomb button.
Spent Shells Shower: The fifth boss of 19XX uses this with a twist after he fires out his machinegun... He fires out the shells forward towards you, making you have to avoid (or just shoot) them!
Stupid Jetpack Hitler: Certain enemies, not to mention some bosses (such as the Gotha/HO-IX) in 1941 fit this trope.
Wave Motion Gun: 19XX has both the fifth boss and the final form of the Final Boss use this on you. Especially dangerous is the final boss' one, as his spins and sucks the player towards it!
Your Princess Is in Another Castle — In 1943, you are congratulated for winning the war after defeating the first 16 or so stages. And then you find out that all those bosses were a diversion from the real army.