Half-Life 2?

from what ive seen, it looks like everything between half life 1 and 2 is just expansion packs to the first and a remake in the source engine, so i think half life 2 feels like more of the second one than these

Xcom 2 is the 9th game in the series

Guilty Gear 2: Overture came after Guilty Gear X, XX, X2, #Reload and Isuka

Pac-Man 2: The New Adventures
Angry Birds 2
Wolfenstein II: The New Colossus
Call of Duty: Modern Warfare II, not to be confused with Call of Duty: Modern Warfare 2

Sushi Cat 2 (Sushi Cat: The Honeymoon came out before it)

Hitman 2, the seventh main game in the Hitman series, not to be confused with Hitman 2: Silent Assassin, the second game in the Hitman series.

Power Punch II.

How would the various versions of Street Fighter 2 count for this?

since they're all just iterations of street fighter 2, which is the second street fighter, they're fine.

Clock Tower II (the 1996 Clock Tower is actually known as Clock Tower 2 in Japan)

HAHAHAHAHAHAHAHA

Also, Metal Gear Solid 2 and Persona 2 belong in this list.

Shinobi II is the seventh game in the Shinobi series