Two things I'd love to see added/changed:

1. Remove the requirement to specify a completion time when marking games as completed. There are countless games I've completed but have no idea at this point how much time it took me. Thus, people in that situation would either have to fudge it some other way (like simply removing the game from their backlog) or enter a bogus time just to be able to mark it complete, which would defeat the point of asking for a time.

2. Ability to specify in one entry of a game that we have it in multiple formats. This has happened to me a lot through some game I already have being in a Steam bundle, or a Playstation Plus game being released in PS4, PS3 and Vita formats.

1) My thinking was the reason behind adding completions is for tracking times in order to build up the database. If you could add completions with no time tracking, it kind of defeats the purpose imho. When I've hit games I've completed and I don't have any means of tracking/remembering how long it took, I just mark it off as finished/completionated in the collection entry itself.

2) I thought about this one as well when I was entering a few of my games that I double-dipped on. However, this would make it a bit messy for tracking things like achievements/trophies if you wanted to track those separately, say if you had something on steam and one of the consoles.
I have a lot of games I've bought physically and finished and marked off as such, but now have digital editions that I would like to go back and play, so I have those marked off as unfinished and backlogged. As such, I have a separate entry for each.

1. OK, I see how to do that now. Still though, I worry about some people adding false times just to put in the completion in the normal way, which defeats the point of asking for a time even worse. At least if they don't enter a time, the site can simply not average in their time with everyone else's.

2. I suppose I could see that point... maybe there would be a way to do it either way. I'm just looking to have everything I own eventually entered in so I could have it suggest a random game I can play next without the games I have in multiple formats having a higher chance of coming up.

1) Good point. I think right now the majority of the site's global features are relying heavily on the honour system that people aren't going to muck about and intentionally skew some values.

2) Maybe use the backlog feature? Right now for the double-entries I have, I set one to backlogged and the other not. Then when if/when I use the suggestion system I just make sure to have it only suggest games that are set as backlog.

It also bears mentioning when requiring a completion point that games without story mode (and even some with), it's really not clear when you "complete" the game. When does one "complete" games like World of Warcraft, Civilization V, Madden or The Sims?

There has definitely been confusion around adding completion times. Some times have been entered with 00:00:00, which is what prompted me to require at least hours or minutes in a range of 1-59. That had a side-effect of not being able to enter 0 for those fields, which created its own set of confusion (even though a blank textbox = 0, it's not very clear on the form).

@dhobo is correct in that the intention behind completions are for collecting completion times and if you just need to mark a game as finished, you should use the progress status. But again, the site does a very poor job of explaining this (which is an issue throughout the site, unfortunately).

I think ultimately I need to re-work that modal so it's clear you're either entering a completion time (which updates the progress status) OR just updating the status since you've finished the game.

Regarding the multiple games issue, this is something I thought long and hard about in the beginning. I have a (bad) habit of buying games on multiple platforms and much like @dhobo mentioned, I try to play each format as I acquire a new one. A great example would be Psychonauts, which I own physically on Xbox and PC, and digitally on GOG and Steam. And yes, I've finished all of them :P Aside from that, physical games really require a separate entry for each if you're interested in tracking completeness / condition.

I hadn't considered the impact this has on the random game selection thing though. I could put something in to suppress duplicate games from having a higher chance of being selected. If one of your duplicate games does happen to win, I could just randomly pick an entry in your collection or something.

I've also received feedback for providing different "views" of your collection. One that's been suggested is more of a shelf view, kinda like the one that's available on GOG. I could see maybe having one that groups games based on the, well, game, so you in the aforementioned scenario, I would just see Psychonauts once, but could drill into the individual entries. The major downside to this is I can't really show things like progress status, platform, etc next to the game, you'd have to drill into it first.

Oh and regarding games like World of Warcraft, The Sims, etc, you can use the "N/A" progress status. The idea with that is it's open-ended and doesn't have a "win" condition. On the Stats page, I actually exclude those games from your completion % since they're not beatable (or at least you've indicated as such). I felt this approach would provide flexibility because everyone plays games differently. For example, I actually marked The Sims 3 as completed once I achieved my lifetime wish, but could totally see someone marking that as "N/A" since it's such a sandbox-type game.

I think the main problem then is that in order to mark a game as finished you need to Quick Add it, then go to your Collection, find it again, click on it (as opposed to Add Completion) THEN mark it as finished. If there would be a way to mark as finished in the Quick Add or Add Completion screens, that would be great.

There's a (poorly named) Status dropdown on the Quick Add screen (on the far-left side), so you should be able to mark it as such when first adding it.

Let me add more confusion ;-) :

0) Debatable is of course the term 'finished', which actually is 'completed' but not really because you can have it 'completionated', a term not really described anywhere. Perhaps you have to give it your own interpretation?
1) I almost always add a completion time, even when I don't remember how long I actually played it. Most of the time I know that it was long or short, and tend to look up the average time in HLTB just to have a time entered. And if I know, most are not accurate as I use timers like within steam and Raptr, but they tend to record playtime not really accurate. Pausing a game? Farming it for Steam-cards before playing it? In the end I just do a guess. Only short games I come close to the actual time, but if it takes more than 4 sits or evenings, it will be a guess. Perhaps you should implement a slider indicating the correctness of the time? Or a range? I definitely would use that.

In the end I will always enter a time, just to get the finished in sync with completed. Just my 'thing' and I don't play games twice (too many games...)
2) This is a bit of a minefield of course as different platforms can have slightly different versions of the game. I'm thinking of XCOM: Enemy unknown on PC and iPad which is the same game but have different gameplays (kb vs. touch). I rather have 2 entries in my collection than roll then into 1 game with 2 versions.

2a) Thinking further ahead, this will be actually relevant when you add DLC which is a sub of a game. Now that you want to relate to the actual game, but also have it separately in your backlog as something you like to play.