The Unity Asset Store has a lot of great assets on it. Which Free ones might be useful to you if you are starting out? There are some really good free assets. It can take a lot of time to look through them all. Their site really could use a major overhaul for discoverability. I am going to highlight some good ones here that you might find beneficial.

At the moment I am trying to build up foundational starting information on various topics non-technical, and technical.

Here are the previous Unity Specific Tutorials if you have missed any:
[Unity Game Development Tutorial: 1] - Assets that are worthy from the asset store
[Unity Game Development Tutorial: 2] - The basics - An Intro to Unity - Layout, Non-Coder, Coder
[Unity Game Development Tutorial: 3] - Optimization Assets, and Particle System Assets
[Unity Game Development Tutorial: 4] - Coding Education Speed Boost - Coding Lesson 1 - also my naming conventions

Free Assets

I am going to go over quite a few different free assets here. I will break them down into sections. I will only list ones I myself have taken a look at. Some of them I may not have done a deep dive into, but I can if anyone expresses an interest in knowing more. These are all free though, so there is no reason for you not to find out if they work for you yourself.

Editor Extensions

This set of assets usually focuses on tools that add to the abilities of the Unity Editor to make your life easier, and make it possible for you to build more things without having to make the tools yourself. They are therefore often one of the most useful kind of assets.

Fungus

How is that for a name? This provides a development interface for crafting stories, and characters without knowing how to program. It is free. That would likely be very appealing to some people. I also consider this as a possible strong tool for making some types of videos for Steemit. You don't have to use game development skills just for games. Using Fungus and Audacity (see free tools engine agnostic tutorial) you could make some cool videos. Here is the official Fungus Website. This seems like a tool that could potentially get many of you just dipping your toes in the waters of Game Development up and doing some simple but cool things pretty rapidly. The fact that it is free is very nice. 5/5 product reviews 147 people
You can visit the asset store page to get this by clicking here.

Noise Brush

This is a simple but useful free asset. If you are making terrain and manually adjusting the terrain mesh this tool gives you some extra options that do not exist in default Unity. The artist/level designer can use this to add a little noise in spots so it looks less like someone manually built the mesh by raising and lowering manually with your hand.
This asset can be found on the asset store by clicking here.

Cubiquity for Unity (Voxel Engine)

I am a fan of voxels. Though I really like to make my own voxel engines. I do own this one and it is free and pretty powerful. If you like voxel games, this might give you something you can start with to diving into it. It can create voxel terrains (e.g. Minecraft like) or retro inspired environments built from millions of cubes. It is open source under the MIT license. It does support cube based and smooth terrain (Possibly using Marching Cubes or Marching Tetrahedron algorithms).
This can be acquired from the asset store by clicking here.

Complete Projects

These are complete projects that have everything you need to get started. In fact on Steam there are often titles like these that are Greenlit and sold to people on Steam as a game. It gives Steam and Unity a bad name when they do this, but consumers need to start learning to do a little research before buying now that making games is potentially free. This means that anyone can decide to get into the game. It is therefore, beneficial to do some research. These complete projects can be a great foundation to build off of and to learn from. NOTE: In this section I do not own most of these. I am listing them based upon reviews (5/5 only). I tend to not need these things, and some of these game types are not in my interest. I am not you though, so you may benefit from some of these that I do not.

Tap N Jump Kit

This is intended for Android, IOS, and WP8. I don't build phone games myself yet. Some of you that may be yor preference. This is a 2D game designed for phones.
You can visit this at the asset store by clicking here.

Complete 2D Side-Scrolling RPG w/ Turn Based Battles and Dialog

This looks like a rather complete project and is actually the game JGA: Crossroads of Destiny which is an open-source side scrolling RPG. Here are some of the features listed.

• A linear cutscene system allowing for long-winded conversations between characters.
• A turn-based RPG battle system with a status effect (sleep)
• A chapter based save system
• Fully keyboard/gamepad controllable GUIs

This can be visited and acquited from the asset store by clicking here.

Save The Babies Kit

This game is based off of "Bouncing Babies" originally developed in 1984 by Dave Baskin.
you can click here to visit it on the asset store.

Polygonix Game Template

This is an interesting little 2D game and looks like it has the potential to show some ways to accomplish some cool concepts. Think what you might do if you want to play around with the art.
You can visit this on the asset store by clicking here.

Scripting

This section generally consists of complex (or sometimes simple) scripts/code that people have made for you to use in your game. I don't tend to use too many of these as my OCD kicks in and I tend to build my own. I have looked at some of these. I am going to only list some of the 5 star ones here. I will indicate in the description if it is one I have actually used. This like the complete projects section above is not something I usually personally benefit from.

Simply A
Pathfinding for NPCs and AIs in your game can be important. Perhaps the single most famous Pathfinding algorithm is the A (a star) algorithm. I did download this package, but I never got around to using it. I have a more advanced non-free asset I purchased for handling this when I get around to it. This is a 4/5 start product on the asset store, yet for pathfinding for FREE I did not ever notice a better solution.
You can visit this asset on the asset store by clicking here.

AesEncryptor

I actually have this one, but have not used it yet. It is a 5/5 star AES encryptor/decryptor for C# and can handle key sizes 128, 192, or 256 bits. The default size is 128 bits (16 bytes). I likely will be using this myself. I wrote my own simple encryptor which is not nearly as secure and I'll likely replace mine with this one.
You can visit this asset on the asset store by clicking here.

Boomlagoon JSON

I know JSON can be a popular topic here on steemit. I also know there are a lot of people that prefer their data represented in the JSON format these days. This is a lightweight C# JSON implementation.
You can visit it on the asset store by clicking here.

DOTween (HOTween v2)

This has a pro version that is not free and a free version. The free version works quite well, the pro just gives you some cool bells and whistles. This is a very effective movement, and pathing (tweening) movement plugin. This is likely something you will benefit from having if you are going to code a lot of movement in Unity.
This asset can be seen on the asset store by clicking here. (Pro non-free version by clicking here)

Audio

The audio section is full of free music and quite a few sound effects. I am not going to go into detail on a ton of them. I will list a few I like that are free here as titles and links.

Horror Ambient Sounds Pack - by Luka Kotar
Lil' Critter SFX - by JP Neufeld
Warped Fantasy Music Pack - by Andrew Isaias
Cartoon Game Sound - by Woong Sound
Cinematic Camera SFX - by Thunder Pop Productions, LLC (Free for a limited time)
Free 8bit Game Sound Effect Package by StrangePulseAudio
Bit Blitzer - by Red Sky Sounds.

3D Models

Most of the really good models have at least some price attached to them. They can be quite low cost. There are however, some decent free models. I'll list some that are low poly style and then some that are more realistic style. There are far too many of these for me to list all of them worth seeing here. I am simply going to share a few that I have checked out myself.

Free Rocks

These are free rocks by Triple Brick and they can look pretty good mixed with your terrain. There are quite a few free rock packs out there. They mostly are all pretty good.
If you would like to see this asset on the asset store click here.

Astra Starship Fleet Package

This artist Daniel Hole Productions has quite a few larger packs of spaceships and stations for reasonable price. Here is a 5/5 star pack that is free.
If you would like to see this on the asset store click here.

Modern Weapons Pack

Depending upon the game you are designing these models by 7XFGames might come in very useful for the steep price of FREE.
If you would like to see these on the asset store click here.

MYFG - Weapon Pack Lite

For your fantasy, and medieval needs this free version of a much larger pack might serve your purposes.
If you would like to see this on the asset store click here.

Relaxed Man Character

This is in a cartoony style but is listed as a 5/5 star asset. It might be useful to some of you.
You can view this asset by clicking here.

Fantasy Monster - Skeleton

This is another 5/5 star free character model. Halloween approaches perhaps this will be useful.
To view this on the asset store click here.

NOTE: There are a tremendous amount of free 3D Models on the asset store. It is difficult to provide you without a truly good sample without knowing what project it is targeted for.

Particle Systems

I touched upon particle systems and their importance in an earlier tutorial where I highlighted some good particle system packs that I own that are inexpensive. This section now has some FREE particle systems.

Elementals

These are some pretty good particles for the price of FREE from G.E. TeamDev.
To see these in the asset store click here.

KY Magic Effects Free

Another batch of 10 game effects by Kakky that are rated 5/5 stars.
To view them on the asset store click here.

Textures

Textures can be really important things. With good textures you can use primitives already in Unity to make games. If you have something like ProBuilder which I spoke about in my first Unity Tutorial then you can do amazing things if you have good textures.

Nobiax / Yughues

I am simply going to link you the the artists page. The majority of his texture packs are free and high quality. I have put these to good use many times. They do also have some packs for sale, but the majority of their textures are free.
To see these assets click here.

Shaders

Shaders tell your video card what it is supposed to do with 3D objects, Lights, and Textures. Without shaders nothing would happen. There are complex shaders and you are going to frequently see the term PBR which stands for Physically Based Rendering which is designed for more realistic life like rendering. The default Unity shader known as the Standard shader now supports PBR naturally. There are sometimes other types of shading people want to do for their games. I am going to highlight a few free shaders here that might help in some of those cases. I already covered one such shader that I will not list here... the Lab Shader. You can find that one in THIS TUTORIAL.

Toony Colors Free

Sometimes you want to go with the toony color style, also known as cell shading. Games like Borderlands use this effect a lot. Though you'll likely want a non-free version to pull off something as good as Borderlands.
To see this asset in the store click here.

Cinema Themes 2 - Color Grading LUTS Library

This one you should watch the video I am providing to explain. It is pretty self explanatory and does some cool things for free. Most of this is a post processing shader. There are some more pricey non-free assets on the asset store that provide tons of features like this.
If you would like to see this on the asset store click here.

Free MatCap Shaders

These are unlit shaders which means they are FAST but they do not respond to the lighting system. Not all games use the lighting system. So these may work great for your needs.
To see these in the asset store click here.

Conclusion

There is an absolutely massive amount of free assets on the Unity Asset Store. What will serve you best greatly depends upon what type of project you are making. I encourage you to explore the asset store. I simply picked ones that I thought might help you or be inspirational. I hope to see a lot more people excited about unity, and/or Game Development on steemit.

I will continue to make Game Development related tutorials as long as their is an interest and people that appreciate the tutorials continue to up vote. It takes some time to make these and so far I am just picking what I feel like making at the time. If any of you have specific things you would like to learn about or would like me to dive deeper into something I have shared so far, please let me know. So far no one has had anything specific so I am on auto pilot and will continue that course until someone asks for something specific.

Happy developing! Happy Steeming!