Rules are automatically enforced:
Boardgamearena: several hundreds of eurogames, family games, abstract games, etc. for all tastes and lengths (many are completely free; a premium account for a few euros per month is needed for some games and further options/expansions)
Boardgamecore: four long-ish strategy games (all free) - unfortunately closed since January 2025 😢
Codenames: homonymous short word game, available in many languages (free)
Rules must be manually enforced by the players - a sort of sandbox table is offered:
Tabletopia: several hundreds of eurogames, family games, abstract games, etc. for all tastes and lengths (many are completely free; a premium account for a few euros per month is needed for some games and further options/expansions)
Tabletop Simulator: actual "videogame" (needs to be installed) to create new games or play some pre-installed classical games (not free - often can be bought on Steam for 10€); several hundreds of board games are developed separately and can be (possibly bought and) imported
Vassal: open-source game engine (needs to be installed) to create new games; hundreds of board games, mainly longer wargames, are developed separately and can be imported (exception: Twilight Struggle is rules-enforcing)
All these websites/apps offer the possibility to create a private table for your friends, as well as to open your game to everybody/join other people's tables.
Still to be tested (try at your own peril!):
Rally the troops: a few historical wargames (all free)
Here is a list of less rules-heavy and more story-based role-playing games. I have played them online (via Roll20 and Discord) since 2018 (after many years spent playing Dungeons&Dragons), each of them for a period ranging from a few weeks to about a year.
7th Sea: players play maritime/piratesque characters in a fictional Renaissance-ish Europe-like continent. They set a flexible "goal" and the related reward (e.g. new abilities) , as well as intermediate "steps" to reach it, in order to guide the GM into the story they would like to play; when fulfilled, they go on setting a new goal/reward.
Nijna the crusade: players play ninjas affiliated to different clans (corresponding to different backgrounds and fighting styles) persecuted by a Asian-like empire. They are awarded new "Wisdom points" every session, depending on the story arc and the actions of their characters, which they can spend to improve their abilities and acquire new ones.
Shadow of the demon lord: players play ambiguous/shady/crazy characters in a horror/fantasy world on the verge of the apocalypse. They start with general archetypal "paths" (= classes) and level up at the end of each session, either choosing new "expert/master paths" (= prestige classes) or improving their basic ones.
Star Wars Forces and Destiny: players play force-users and non-force-users in the classical Star Wars universe. They obtain new XPs every session, which they can spend in a technology tree to acquire new abilities.
Heart: the city beneath: players play "weird" characters in an Underworld filled with various (magical) struggles between order and chaos. They select a couple of minor/major "beats" (short/long-term objectives) at the end of each session, influencing directly the story the GM is preparing for the next sessions, and obtain new minor/major abilities after they have fulfilled them.
Legacy - Godsend: players control two different characters: a minor god, involved in divine politics to extend their influence and increase the people's Faith in them; and the avatar of another player's god, wandering the Earth to spread their dogma, convert people and shape the Fate of the world. It is set during an Age of Creation or in an apocalyptic transition between old and new worlds.
The One Ring: players play Tolkien-inspired characters in the wild region of Eriador (north-west of the Middle Earth, including the fallen kingdom of Arnor, the Shire, Bree, Rivendell and Lindon), in the tense time between the events of The Hobbit and those of The Lord of the Rings. The obtain new XPs every session, which they can spend during the "Fellowship Phase", taking places after a series of adventures, to improve their abilities.
In most of the game above, to determine the (in)success of their actions, characters roll a pool of various dices, possibly removing some of them and comparing the (sum of the) results against a set difficulty. However, unlike in the classical d20 system, these procedures result mostly in positive/negative narrative outcomes and less prominently in numerical effects (even during battles).
Movies inspired from RPGs:
Dungeons&Dragons: old animated series
The Gamers, The Gamers: Dorkness Rising and The Gamers: Hands of Fate: films satirising (bad) roleplaying
Humans&Households: webseries reversing the roles of players/characters
D&D 3: the book of Vile Darkness: only good film of the entire film series
D&D: Honor among thieves: reboot of the previous film series, set in the Forgotten Realms and full of actual in-game references
Dark Dungeons: short film satirising the 80's-90's moral panic over RPGs, exemplifying Poe's law
Webcomics inspired from RPGs:
DM of the Rings: webcomics explaining why LotR would not make a good D&D campaign
Darths and Droids: analogous project for Star Wars
Order of the Stick: webcomics following a group of adventurers through various D&D editions
Others:
Roll20: to play role-playing games online (allowing to upload character sheets, move character on a map, roll dices, etc.)
d20 SRD: system reference document (incorporating the entire rules system/information of the basic handbooks) for the various editions of D&D
Databases:
Boardgamegeek: comprehensive database of board games
Rpggeek: sibling project for RPGs
Videogamegeek: sibling project for videogames
Traditional italian card games (mostly using italian/spanish card decks):
Briscola: a point-trick-taking game for two to four players (unusual characteristic: players are not required to follow suit)
Briscola chiamata: variant of briscola for five players (introducing a bidding phase to decide the trump suit and forming the teams)
Scopa: a fishing game for two to four players (unusual characteristic: points are scored in five separate ways)
Sette e mezzo: a Blackjack-like push-your-luck game for two or more players (less strategic than the previous ones)
TGC games online:
Pokemon: free to download (in all operating systems), allows to play the classical Pokemon TGC game (including all the new generation cards) both against AI and real players online; one starts with a few pre-made decks and can win/unlock new cards inside the game to refine/build new decks
Yu-gi-oh games: full list of video games (the Game Boy ones are easy to find via emulators) allowing to play the classical Yu-gi-oh TGC game against AI players, building your own deck; I appreciated in particular "Yu-Gi-Oh! GX Duel Academy"