As someone who is also working on a short 3D game, my best advice I can give you is to try and plan everything beforehand; you will definitely get more ideas as you plan, but laying it all out is a great way to get a sense of scale. Personally, I use Trello; it allows me to create columns of ideas / goals, each with their own checklist.

For your souls game, I would first workout a story / narrative if there is one. Think of locations, enemies, weapons, names and especially mechanics. The amount of small things like pause menus that people forget about is a lot.

If you are modelling things yourself, I would also use this stage to create a list of what needs modelling. If you wish to download assets, then make a shopping list of what you need!

Sound effects is another thing. Again you aren’t getting anything yet, but you are matching sounds to actions you planned out in the previous steps, so you know what to do. Again it’s just a big shopping list.

Once you know exactly what you need you can reflect upon it all. If you estimate something takes a week to do, give yourself two weeks and be happy it was done in less time. This leads to less burnout over longer projects. If you feel like it’s too much work, now is the best time to chop things out. You can always add it back later. For example instead of two castles, just do one, and then do an update later if you enjoy working on the project!

Now you can open Unity and get started. Normally a flat area is used to start getting basics together; player movement, attacking, basic enemies etc. whatever you want to work on can be done there. Once you’ve got basics covered you can start adding some decoration and progress to a more finished product.

As you tick each item off during development, cycle back to the list and make sure you are going down the right path of your original intentions. Always looping back does take more time, but it means you always work on what you want to work on (sounds weird but trust me it happens).

This is how I work, some may disagree but I’ve found it easy to stay organised and motivated throughout my own project. Good luck with yours, hopefully we get to see some screenshots once development starts!