INSPIRATION VS. RIPOFF

I recently played two games that were very similar in the pack used, the setting and the game-frame - these two namely being Lunar Quest and Star's Favour. Two dungeoncrawlers set on the moon fighting slimes of monsters to clear the holy temple grounds. Both had a level-cap of 5, and fairly small dungeons with only on-touch encounters that you fought at will.
Lunar Quest took a lot of inspiration from Star's Favour, and ended up as the better and more fun game of the two. And apparantly it also spurred a debate of whether the creator was ripping the other game off or not, which I find a little disheartening, but it begs the question as to what a ripoff actually is, or is not.
Rips in graphics seem less popular, but fan games and other inspired games are and always will be around. We are affected by the games and concepts we like, and admitting this to be the case makes things only easier. It also helps for players to identify things they like and can make it easier to explain and gather interest. I'll get back to the two games in question, but before that we need to clear things up a little bit.

Where does inspiration end and ripping off begin?

I suggest the whole building concept of a ripoff is inherently different in mindset than it is to take inspiration. Ripping off means to copy what you think is good, and then add little of your own. To take material as it is without understanding it, understanding why it is used, how it is used, and how it works in synergy with other aspects. And thus usually without finding proper use for it.

It is also part of the reason many ripoffs fail as a game - looking at the many simulations trying to copy the success of "Surgeon Simulator", for example. They are played as a joke of a joke, when much of the original game's success was because such a game of "worst controls on purpose" has not have made it into the spotlight before. It was unique. As well as the fact that it makes for a really morbid combination between the seriousness of the situation - treating a patient in a life-death situation - and using intstruments like a 3-year-old at best, playing with ribs and bones and organs, blood spilling everywhere. Surgery is also an inherently tricky trade. Trying to play the same joke we now already know in a far less fun environment is not going to work. There are a few games establishing their own jokes, but they need to build something on top of such concept if they want any chance at success.

Understanding why it works so well allows you to transition from copying aspects, to actually integrating them into your game. And then there is taking aspects and adding your own concepts and ideas on top of it. I would say there are inherent traits that simply work so well you may very well use them together with your own ideas - they usually come in abstract form, too.
Say, there are dungeon crawler utilizing a sense of danger system - indicating when a fight draws nearer with a color shifting from green to yellow to red. It does not affect the encounter rate itself, but allows the player to anticipate attacks and plan to heal themselves if need be. It also allows you to see if you want to traverse the room further to get chests, or procced to another room to reset the counter. You may think such a system is a great idea and add it to your own game - and I think that is perfectly okay to do.
Yet again, if there is no way for players to prepare for fights (say, they are healed automatically and have nothing to change beforehand anyway), if you are on set paths, and if battles are easy and clearly not the focus of the game, then this feature is obsolete. It seems like a wasted effort. It may look nice, but players will act the same.
Of course, legally, taking other people's precise ideas, crafted resources without crediting is an established no-no. Plagiarism is a thing. Yet often the inherent underlying concepts are not unique to a person - like making a game focused around battles with only one character. Or two, or having a light-hearted tone, or a serious tone. I am not well-versed enough in the subject to define the legal differences properly, so I will just leave it at that and speak more in creative terms.

So, about those two games..

Let's get back to what we were talking about - the games look and sound really similar, and so does the setting! Part of this feeling is due to the graphic assets used: enemies, tilesets, character sprites and music files are all from the same pre-bought package - making the setting much more accessible (that being the moon), and giving the two an at first glance same appearance. It is also far less common than the RTP making this similarity standing out a lot more.
There is the party of four with a light-hearted tone. A party of four characters is too common to bat an eye or to really make a big difference, and a light-hearted tone is really a matter of preference and both play this out in their own ways (lesbian in-your-face romance and relationship to spell/skill mastery vs. wanting to beat things up), with less dialogue on Lunar Quest's part.
Now the story is similar, but how it is introduced and treated is quite different from one to the other, hinting at a different world / galaxy system.
In Lunar Quest star sisters require your help to restore their temple and guide you to it - the quest itself is serious, even if the hero party is just there to punch stuff, return a favour and then go home.
In Star's Favour a star-clan-people-stuff require your help, but the leader of the operation left you alone with the task at hand. It turns out to be a long-lasting quest, too, one you didn't really want to take on to begin with.

But more than that, the gameplay at the core of a dungeoncrawler plays out completely different, which actually makes it a perfect demonstration of how to take an idea and let it evolve it into something else.

There are two core ideas that were taken over - the first being that the monsters are fought very purposefully - you can save anytime, nothing chases you and there are no random encounters.
The second being that the level is capped at 5 - adding to the very thoughtful progression and making grinding only a limited option. It also makes it all very easy to keep track of.

How these are then integrated into the game is a different story as there are major differences in the system. The list of actual spells, too, is vastly different, with Lunar Quest having a far greater emphasis on ailments and dot effects.
In Star's Favour learning new spells is NOT tied to level-ups, but to battling special monsters. Items replenish themselves, and you are always fully healed after battle and will be revived. There is equipment to find.
In Lunar Quest new spells are learned on level-up, you find items (no equipment), you have no way to regenerate mana/health with spells outside of battle and need to use items, or manage your health/mana infight, as there is a light mana-regeneration spell.

This drastically changes how you approach battles - in Star's Favour the battles themselves do nothing outside the battle screen. They are a necessary evil to procceed to treasure chests or towards bosses. There is nothing to be gained in it, and they have no impact long-term, either. Instead you focus on each battle as a challenge in itself to use everything at your disposal every time. Sadly they end up being a drag because the fights themselves are long-winded and without many spells to use for the most part.
In Lunar Quest every fight you pick is a trade-off - grinding for exp to gain access to stronger spells, but needing to use items. Reaching additional treasure chests (they are plenty unguarded, too) was a trade-off between gaining enough items to make up for the fights. As well as keeping your party healthy while battling your way through. The battles (as in Star's Favour) ended up being too easy to use all this to their full potential, but the concept and layout makes the two very different. Lunar Quest's battles themselves were a lot of fun keeping an eye out for the ailment-micromanagement, even if they are easy.

Both keep the concept of a very clear overview of what you can do in and outside of battle, both let you procceed at your own pace, carefully planned as you pick your battles. But both end up having a completely different battle-system regardless.
Since the lack of hostile monster allows for this careful procceeding I think Lunar Quest does a good job of building its system in synergy to that.


But where's the creativity!

It seems to me that often times taking ideas is looked down upon, and crafting things from scratch is always welcomed. This is, of course, also a great way to go about it, but creativity is channelled in different ways.
Creating limits, rules and a frame for you to work in that are not original - requires you to think outside that box and in creative ways to still make it your own. Working under restrictions can actually make you come up with unique creative ideas to bypass and build around the restrictions - in fact, creativity strives under such conditions! It makes you use your creativity in a different way.
I think taking advantage of this, and being bold enough to work an idea into your own is a great asset to one's gam mak.

I think the most apparant examples of this are straight fan-games - let's take a look at the Pokemon RMN version. It is incredibly tight in its frame. It is a straight carbon-copy of Pokemon gameplay, system, exploration and more. From the graphic assets to color pallettes and resolutions - it is Pokemon.
But the aspects that can be changed are used to great extent to express and tweak the experience towards something great.
Kentona being a sluggish clumsy rival for example adds its own sense of humour and purpose in regards to rmn. The pokemon themselves have a great variety from classic designs to "hypsters" and all kinds of references and jokes additionally to complete original critters that look like they could actually be part of the original series. And I will be honest and say I am really psyched to play it when it is done, as it adds so much flavour to the game (and I have been ignoring pokemon as a series every since .. ruby?).

All that said - before you integrate ideas, stop and think.

- Why do these aspects work in the game? Are there any synergies?
- What does it add to my game? What effect will it have?
- How can I improve the aspect or tweak it to fit in?
- What can I add to the game that works together with the aspect?

If you take it because it looks cool, and you like cool things, stop.
If you evolve the ideas used, if you add on top of them, then you are crafting your own game and are just inspecting what bricks to build it with.