Great suggestions for means of creation already on the forum! And as I enjoy finding out about these sorts of things, here is a short list of various ways I have used to make music or create ideas you may/may not know! These can be used for your Demo production, as a rough first draft can be the initial seedlings for later polishing into a jem of a finished piece. Some aren't entirely linked to demo production per say, but could help with the creation between idea stage and demo production. Apologies if I posted in the wrong sub forum.
1] Alternative DAW Software through Video Games = Music 2000 Playstation 1 / Beaterator PSP / Dreams PS4 / Korg Gadget Nintendo Switch / Gameboy Camera
For those with more of an incline for controllers and the use of games consoles, these games span from being pocket DAW to more advanced. Some of hese are more than music creation software and allow for other sorts of creations, like Dreams seems very advanced and I couldn't figure it out, but the others are more user friendly and allow for creation of music either through self input on a timeline or samples. If you happen to have these knocking about somewhere or even fancy spending a little money to having a play about with em, worth a shot!
2] Board/Card Games idea generation = Bard Cards / Story Cubes / Mozart Music Generator
For the more systematic or on the fly improvised approach, these can allow for some interesting results! Story Cubes and the alternatives are great prompts to create quick ideas based on dice rolls. You use them as you like, and I like making a system to apply these tools Mozart Generator is a good way to see music differently, with sonatas being the classical form of piano and harpishchord music back in the day, create like a genius! I do mean to buy some Bard Cards when I eventually get spare funds, they'll be a good addition to my small collection of offline generators!
3] Other means of challenges in creation, NaNoWriMo / Inktober / ArtFight / Game Jams
Other creative challenges may be worth considering while undertaking or separately done from 50/90, because this can spark other ideas from other sources. Art and drawing, sculpture, game creation, character creation, world building, etc, is a good way to think of art from a different angle, and by learning another medium to be creative adds an extra dimension to your creative insight on matters. Helps in looking outside the box or maybe even box ticking or categorizing if you prefer to label things in certain ways.
4] Written form, Bullet Journal / Sketch Books / Every Day Notepad Carry
Some may use these already, but by carrying either of these along with you, an idea you may have when out and about or doing housework etc, this gives you a means to write down ANYTHING you like. A profound quote, TV shows and media references you like, a journal entry about your day, things you want to remember later, research topics, a subject you want to read up on, lists of song title ideas, whatever you want to get done, a notepad can save you time and effort. An alternative to this is to just rely on being able to remember, because sometimes things stick out in your mind for use later without you needing to write anything down and stew around a while, later to flower a great idea. Either way it's a tool that can be used for anything you assign it to. Go Nuts!
5] Concept Albums / EPs
Thought I'd include this as it's a fun way to look at creating ideas.... There is a history of the concept album all over the world that still gets used as a medium today. Should you not be aware of examples, type in list of concept albums wikipedia in your search engine. There is a huge drove of ideas just waiting for you to look at music from another angle. Exploring lyrical themes, fictional worlds, social commentaries, interpretations opinions etc, find something you like the look of. Genres such as Prog Rock, Hip Hop, Pop, Metal, and countless others use concepts to make their albums tell a different story. What would you like to explore as a concept? Anything goes!
Feel free to contribute to this thread! I'd love to see your alternative software/prompts/tools and ideas, things I haven't thought of before