Small game or low content doesn't necessarily mean unfinished but sometimes it's very clear when a feature or a section of story was cut out due to time or budget constraints.

Missing Essential content- Mass Effect 3's Labrynth DLC should have been part of the game, its a crutial part of the narrative and looses a lot of its muster and awe once you've already completed it.

Bug filled games, although massive open world games get a bit of slack. If there "needs" to be a patch because the bugs are so severe then that is unfinished IMO

FPS problems. Some games will simply struggle to run certain stuff on X hardware, thats fine although developers should work around this (lower graphics), but if a game is released and for unknown reasons there are huge FPS problems that can be resolved with a bit of tweaking with a patch (AC Unity), that shows me the game wasn't tested properly.

- a big Day-1 patch
- bugs everywhere

Cool thread.
Unfortunately I do not think there is a very clear cut answer. Ultimately an unfinished game to me is one that provides a heavily inferior product to what should be the norm in that genre (price can affect this). To illustrate my point, i will provide 3 examples:

1) a game can have bugs. In fact, most games will have bugs due to the fact that there are major coding projects involved in making a game. This does not mean that a game is unfinished. Take super smash bros melee. Wavedashing is perhaps the most notable bug (sakurai saying it wasn't supposed to be in the game), but it is a bug that has skyrocketed the melee competitive scene and has, quite frankly, added to the melee experience. Super mario 64 also had the backwards staircase glitch, but that instead added to the competitive speed run scene. Noone is calling those two games unfinished.

2) a finished product is not set by the guidelines of the maker. Take project cars on wii u. They have the game running at 23 fps. SMS could have set that as there goal and called it a day, after all, there are no bugs with it and it still has the 'core' project cars experience. But they know that to do that would be to release an unfinished product, because that framerate is not a standard in most racing simulators. So they made the decision to notify people about it instead of selling it.

3) a product is determined finished by what is comparable to it upon release. Splatoon is not finished in its current state. I can make a comparison chart between the $40-$60 splatoon and the $20 black ops 2, and we will see one heavily out weigh the other. The comparison doesn't have to be black ops 2, it could be titanfall, or destiny, or halo, or borderlands, or ... the list goes on. No splatoon does not have to be as content packed as those games, but when voice chat is a standard, when customizable local matches is a standard, when over 5 maps is a standard, one can argue that splatoon does not reach a standard in the shooter genre and can therefore be argued as unfinished.

bug filled games...Ac Unity and Battlefield 4 left a bad taste in my mouth.....

If a game requires multiple patches to quash major bugs (aka crashing, save corruption, freezing, or impossible to 100%), it was very obviously released in an unfinished state. Recent examples include Apotheon & Ether One on PS4. (There are still a few huge issues with Apotheon, but Alien Trap doesn't seem to care...so the game is finished yet broken.)

Technically, I'd say any game that hasn't received it's final patch or DLC is unfinished, but I think we're looking for a more negative definition.

A game like Mortal Kombat X is tricky. If all the DLC was released, it would be finished & hugely overpriced (with the core game being incomplete). 

Halo Collection on xbox one is an unfinished release.

Gothic 3 is among my favorite games of all times, yet when I first played it it was broken to the point where I couldn't be bothered with it. Two large patches later and it was suddenly amazing.

Open world games usually have huge issues in the beginning, so many things can go wrong.

Massive bugs and non-accessible game modes. Also anything released with Day 1 DLC.

It all depends on context.