The #Galactic-Milieu presently uses two trading platforms: #HORIZON and #Stellar; lets take a look at both and try to highlight reasons why or why not to choose one or the other of them, and consider whether to even go ahead and use both...
#HORIZON is the platform the #Galactic-Milieu migrated to when first moving on from the #Open-Transactions platform. It is a "NXT clone", which featured a very egalitarian startup in which the initial one billion HZ tokens were distributed over time to any "node" anyone chose to deploy; thus basically anyone with just a small amount of technical know-how was able to deploy a "node" and start earning HZ tokens.
Various factions within the #Galactic-Milieu chose to deploy #HORIZON nodes, so between the various major players and player-groups quite a number of HZ was accumulated by the time all one billion HZ were distributed.
Thus #HORIZON was an easy choice for a platform to migrate onto from the #Open-Transactions platform since not only was it free, open-source, and had a very egalitarian initial distribution of HZ but also a large amount of HZ was available with which to pay the platform fees involved in setting up a large number of "assets" on the platform.
See https://MakeMoney.knotwork.com/horizon for pages about the various assets set up on the #HORIZON platform, but note that #HORIZON had two types of token, named "currencies" and "assets" respectively, and it turned out that so-called "currencies" did not work. We have never yet bothered to fix them, as so-called "assets" work fine for our purposes; but note that the things listed under https://MakeMoney.knotwork.com/horizon/currencies are broken, do not work, are not used; it is the stuff listed under https://MakeMoney.knotwork.com/horizon/assets that actually work and are actually used.
An important thing about the #HORIZON platform is that it is intended that you run a node yourself. You can see an example node at http://lfm.knotwork.com:7776/ but you should not use that node for real accounts or transactions for two reasons:
One, it is only an HTTP site not an HTTPS site; that is, it is not secured by end-to-end encryption between your browser and the node. That is deliberate, in order to cause your browser to point out to you that it is not secure!
The reason the #Galactic-Milieu deliberately leaves it as an HTTP (insecure) site is that it is not hosted on physical servers that they physically house themselves. It is on a dedicated server they rent from a hosting company, located in one of that company's data centres, and thus the #Galactic-Milieu has no control over who has physical access to the machine thus no control over what anyone who has such access might or might not do to it.
It is physically possible that some employee or owner of the hosting company hosting the server could tamper with it in some way, such as by recording a history of what passphrases were used on it to access HORIZON accounts through it. HTTPS end-to-end encryption would not prevent that!
You are intended to run a #HORIZON node yourself because then you have some control over who can physically access it, or at least maybe some knowledge of who could physically access it. If you do not open your internet-facing firewall to allow incoming user-interface connections to your node from outside your house only machines inside your house or connected to your WIFI network will have access to your node, and only snoopers on your own network could watch passphrases going by over the network.
HORIZON is written in java, so is considered platform-independent; almost any common modern operating-system you happen to be using should be able to run it. So you are intended to download it for yourself, configure it, and let it catch up to the blockchain. If that seems a little too technical for you, you might be better off looking at the #Stellar platform rather than ignoring this security warning and blithely using someone else's HORIZON node over the internet.
#Stellar is also a "clone" platform, in this case a Ripple-clone. However unlike HORIZON it did not fade into obbscurity and thus become a great candidate for game use; #Stellar is to this day still a first-page platform on #Crypto listing sites such as CoinMarketCap and CoinGecko.
Like #HORIZON, #Stellar was commended to the attention of the #Galactic-Milieu not only by its ethos (Ripple, by comparison, being rather too "big brother -ish", especially once they stopped offering a desktop client you could run for yourself on your own machine in your own home) but also by the fact that thanks to a very early giveaway on BitCoinTalk forum when Stellar first came into existence enough Stellar Lumens (XLM) were available to the #Galactic-Milieu that issuing its tokens on the #Stellar platform seemed at least marginally feasible.
The feasibility problem was not any kind of platform fees associated with minting tokens, since #Stellar's fees are trivial, tiny, miniscule, and there is no actual fee for minting per se. The problem, and we are still facing it today, was and continues to be the simple fact that the #Galactic-Milieu as a whole does not really have a whole lot of Stellar Lumens on hand, thus building up good strong "buy sides" for all the tokens is a rather long-term project.
It is, however, a project that presents us with opportunities; because the #Galactic-Milieu is currently still in the "build the buy-sides" phase of establishing its tokens on the #Stellar platform, and still has a long way to go to pile its buy-offers on #Stellar all the way up to the actual calculated values used by the game in pricing game offerings in terms of the various assets and currencies, a whole lot of its assets are still massively underpriced on the #Stellar platform.
That means we can each individually apply a strategy of systematically building up the buy-sides and reasonably expect to profit by doing so.
This is not financial advice!
It is simply pointing out as players, to players, that playing the "build the buy-sides" game is yet another #play-to-earn opportunity within the #Galactic-Milieu.
In #HORIZON, all trading-pairs are pairs of one asset or currency against #HORIZON's own native coin HZ.
In #Stellar, you can pair anything against anything else, thus if you wish to you can avoid even trying to figure out a value in #Stellar's native coin Stellar Lumens (XLM), simply pricing one arbitrary thing versus another without needing to know or guess how many Lumens either one might be worth. This can be very handy for players just looking to exchange one game asset for another without regard to the platform's Lumens other than as something to need a tiny amount of to cover transaction fees (and of course something to need one of to have an account at all and half of one of per game asset you want your account to be able to use).
Enough for this post. Hopefully this has given you at least a glimpse of what these two platforms are and thus helps you choose among them.