There's a whole world of different games of different genres, from card games, to board and dice or role playing adventures that you can play at home for little or no cost.  An example of a few games with an extremely small investment are 3 that can be completely printed out on maybe 5 or 6 pages,  If you only print the playing components and not the rules some require only 1 or 2 sheets of paper, though some may need to be double sided.  There are many styles of print and play games from ones that have multiple players or can be played solitaire as well as ones that have maps to explore or are themed around space or fantasy etc.

Boardgamegeeks is a very popular site: Print and Play at Boardgamegeeks

Another family of sites that have on-line downloadable games, many are for free are the "Drive-Thru" sites.  Here's a link to Drink Thru RPG: Drive Thru RPG

Here are 4 quite small print and play games I've discovered that only require a single sheet or two of possibly doubled sided printing for the game components.  The rules are oftentimes less than a half dozen pages as well, so you can print the rules out too, if desired.  Some of these also need dice but you probably already have dice around ... if you're super hardcore, you can actually print paper dice - I'll let you search for how to do that on your own ;)

The one that recently resparked my interest is One Card Dungeon.  It only requires one double sided piece of paper to print the map but it may require up about 11 dice ... Luckily I already bought a pack of 10 dice at a dollar store, so I'm good to go.  The rules are short and can be memorized:

Here's a playthrough of One Card Dungeon but just watch whatever's interesting

Count of 9 is composed of 9 double sided cards that can be printed on a single page and doesn't require any other components like dice or a board etc.  Quite amazing to see what can be done with just 9 cards.

Pocket Landship is another I've played quite a few times.  It only needs 1 double sided page for the cards but an expansion adds a second sheet for 9 more:

Mini Rogue is another very small one requiring only 9 cards printed on a single page but a second sheet is very useful to keep track of various resources, levels, health etc.  So it's basically a game with 9 cards and a second sheet for scoring and keeping track of data.  The reviewer "Marcowargamer" or "Marcoomnigamer" has a lot of great content on his channel and I even bought the game "Four Against the Great Old Ones" that he created - great purchase.  Check out his channel if you're a gamer (especially if you're interested in solo play)

That should be a decent enough introduction to the hobby.  There's a lot to it and one suggestion is to feel free to modify the game and rules to make it something a bit of your own.  It was called "House Rules" back when I was playing Dungeons and Dragons.

Mostly it's about having fun and if you can do it with a deck of cards, a few dice or couple sheets of paper, congratulations.