Chapter 3 Text
Games can and have stored their text as simple graphics but developers learned quickly that for longer games this is not very helpful at various levels so games have long featured text decoding and display engines. Said engines are very often highly custom things with various abilities and restrictions that people hacking them have to figure out and are second only to the game level files and assembly in terms of how custom things can get. Games still have text in the images they might display, very often for low text games like puzzle games but not always and anything highly stylised is probably graphics, and conversely some early hackers altered the encoding of characters to have them appear as others in certain places (often messing up the text in the rest of the game).
Never the less text engines are very much a part of games now and as such aspiring ROM hackers have to know how to deal with them. Know that games can and do often enough use multiple versions of the following concepts within the same game and even on the same screen at once.