References to previous games in a series/related games

[velcrozombie1]

I don't know exactly how common this is, but there are two specific instances I can point to:

1. In River City Ransom, on the top floor of the high school, the main theme from Double Dragon begins playing once you defeat all the minor enemies. You then proceed to fight the "Dragon Twins". Technos developed both Double Dragon and River City Ransom, although I have no idea whether these characters are just an in-joke reference or if these two franchises exist in the same continuity.

2. Stage 08 in Castlevania III (Entrance to Dracula's Castle) is a short, relatively easy stage that gives you a breather before the nightmarishly hard final levels. The stage looks vaguely similar to the first stage in the original Castlevania game, and the music is a pumped-up remix of the track from that level.

[Rev1]

This happens quite a bit. Some examples I can think of off the top of my head would be:

1. Mega Man 8 (Saturn)- you can fight against Woodman and someone else from Mega Man 2.
2. Mega Man 3 (NES)- fight against all the original robot masters from MM1 or 2.
3. Castlevania Dracula X (TCD)- once you get to the 6th stage you fight all the original bosses from Castlevania 1.

[mbd361]

The first game to do this is "Atlantis" for the Atari 2600 which references "Cosmic Ark".

[Calysma1]

• In the original Uncharted game (Drake's Fortune), the wetsuits worn by Nathan and Elena at the start of the game carry the fictional brand name "Ottsel" on their fronts, a reference to Daxter from Naughty Dog's previous game series, Jak & Daxter.

• Game Freak placed references in their Pokémon games to at least two of their non-Pokémon titles: 

1. One character in the original Red & Blue games is playing on their SNES "a game with Mario wearing a bucket on his head", a reference to their 1993 Super Famicom game Mario & Wario (released only in Japan).
2. In the most recent games, Pokémon X and Y, one character mentions he's recently been playing a "sweet game" where "you play as this cool little dude who runs around and whacks enemies to the beat of the music," a reference to their most recent non-Pokémon game, HarmoKnight on the 3DS eShop.

[Rev1]

Ah, another fun example would be in Pokemon Gold/Silver, after you beat the main quest you can go back through Kanto. This was an awesome idea and even though it felt rushed, really added some fun to the old games.

[Vexer1]

In Splinter Cell: Chaos Theory, Lambert warns Sam not to get caught and Sam replies "what three alarms and the missions over"?(which was how the alert system in the previous games worked).

[kew9820001]

I just recently played The Legend of Zelda: Ocarina of Time for the 3DS. I can recall pictures of Mario in the window when you first encounter princess Zelda in the garden as a child.

[HardcoreSadism1]

James Seth Lynch and Kane can be spotted in Hitman: Absolution. You can even kill them in Contracts mode.

[Vexer1]

One of the secrets you can unlock in Jak 3 is a Ratchet and Clank gun course.