Mostly linear
All-Ages
A minor amount of gameplay interaction
DDLC Plus Side Stories unlock after doing certain events in the main story
While often remembered for its biggest twist and final sequence, this free VN does a surprisingly nice job in its quieter moments and has a genuinely likable cast.
The original is OK, it's good for casuals but maybe may not as good for experienced readers. However, I really liked the Side Stories in DDLC+, being a lot more character development focused on the main 4 heroines with some nice heartwarming moments.
Good starter VN to introduce the format to people. It's short, free, and doesn't really have any extreme or adult content. Only a couple moments that get pretty freaky if you walk into it blind.
Original (100% Free!) - https://store.steampowered.com/app/698780/?utm_source=vndb
DDLC Plus Steam - https://store.steampowered.com/app/1388880/?utm_source=vndb
DDLC Plus Switch - https://www.nintendo.com/store/products/doki-doki-literature-club-plus-switch/