The Difference a Portal Makes
One of the main reasons I think portals are so cool is the amount of difference they make in terms of the difficulty of the level.
The difference is particularly noticeable as you progress through the first 3 packs in the game. The number of portals is constant within each pack:
The Beginning: 1 portal
Double Trouble: 2 portals
Tripping Out: 3 portals
I played these packs during testing – which in addition to tracking the score, also tracks the time it takes to solve each level. Here are the results:
| Pack | Avg Tiles | Avg Time | % Perfect | Time/Tile |
| The Beginning | 74.3 | 17 | 100% | 0.23s |
| Double Trouble | 98 | 44.7 | 89% | 0.46s |
| Tripping Out | 111.6 | 69 | 67% | 0.62s |
The Beginning introduces the portal. Once you learn the basic concept, the levels become almost automatic.
Then you reach Double Trouble – and suddenly you’re forced to think. Relative to the size of the board, it took me twice as long (or should I say, caused me “double the trouble”) to complete each level in Double Trouble.
Tripping Out – the craziness of portals is on full display here. After cruising through The Beginning in about 40 minutes, Tripping Out took almost 3 hours to complete, and I had to use hint mode for 1 out of 3 levels.
And these are only the first 3 packs – the levels get crazier in the later packs – though the next 2 packs are easier than Tripping Out.
Here’s a generalized chart based on all types of levels in the game:
| Portals | Tiles | Time | Time/Tile | TT/Norm | % Perfect |
| 1 | 73.1 | 17.6 | 0.241 | 1.00 | 99% |
| 2 | 98.3 | 45 | 0.458 | 1.90 | 87% |
| 3 | 114.4 | 69.8 | 0.610 | 2.53 | 55% |
| 4 | 137.9 | 100.2 | 0.727 | 3.02 | 27% |
| 5 | 183.9 | 138.7 | 0.754 | 3.13 | 13% |
TT/Norm = normalized time/tile, as a factor of the time/tile of 1 portal.
The Effect of Board Size on Time/Tile
You might notice from the above chart that as the number of portals increases, so does the average board size. Could this be the reason that the time increases so dramatically? It turns out, the opposite is the case:
I didn’t include 5 portals in the chart because there are few data points across a narrow range of board sizes.
The chart shows that the average time/tile decreases with the size of the board at 2 or more portals (the trendline is slightly positive for 1 portal, though hardly statistically significant). The more portals, the steeper the rate of decline. There are sample size issues here – some of the individual points are based on as few as 5 levels played.
The reason: as the number of portals increases, more time is spent figuring out how to cross the portals than filling the rest of the board.
The Effect of Board Size on Percent of Levels Perfect
Conversely, the larger board size averages for higher number of portals does increase the gap in percent of levels perfect:
I excluded 1 portal from this chart because it’s a flat line at 100% (with 1 data point at 92%).
Interestingly, the trendlines are nearly continuous if you start at the end of the previous trendline. This feels about right to me: the first 30 levels of Tripping Out are fairly equivalent to the last 30 levels of Double Trouble in terms of difficulty.
I will be the first to admit that these data are hardly scientific – I am a human and I played these levels with full knowledge of what to expect (at least, after I played enough levels).
Still, even with small sample sizes there is almost zero overlap in both of the above charts – exactly 1 point per chart:
At a board size of 9x12x2 (216 tiles) I averaged 123.5 seconds over 8 levels with 3 portals, and 116.6 over 15 levels with 4 portals.
Even more surprising is the lack of overlap with percent perfect – given that each level is either a 1 or 0 as opposed to a time.
The guilty point in this case comes at 8x9x2 (144 tiles). I scored perfectly on 10 out of 21 levels (47.6%) with 3 portals, and 4 out of 8 levels (50%) with 4 portals.
Count of Levels per Number of Portals in the Game
Personally, I prefer the range of difficulty from 2 to 4 portals the most, which is why most of the levels in the game fall in this range:
| Portals | # Levels | % of total |
| 1 | 250 | 15% |
| 2 | 449 | 27% |
| 3 | 451 | 27% |
| 4 | 331 | 20% |
| 5 | 122 | 7% |
| 6 | 47 | 3% |
Average portals for the entire game: 2.86.
If it weren’t for hint mode, I probably wouldn’t want to play any levels with more than 3 portals.
On the other hand, the time to solve the puzzles based on the number of portals is probably fairly accurate (for me, at least).
The Portal vs. The Bridge
If you’re familiar with the Flow Free series – CTD: Portals might at first seem comparable to Flow Free: Bridges – a slight variation of the original Flow Free.
Connect Unlimited is the first Connect the Dots game I wrote, and it’s essentially the first 3 of the Flow Free games combined in 1. During development, I did a lot of testing to see the effect of the board size and bridges (and for the hexagonal levels, “crosses”) on the time it takes to solve each puzzle.
Bridges undoubtedly increase the time – but they do not approach portals, capping at about 25% additional time over levels without bridges.
Hint Mode Isn’t Cheating
If you find the levels in CTD: Portals too hard to solve without hints – you’re not alone. I developed Hint Mode and the scoring system for this reason. In CTD: Portals there is only hint mode – as opposed to the 4 options (including validation) in CTD: Shadows. I don’t think the others are necessary with hint mode – there are cases where you could be tricky and save a few points using validation mode, but that’s not really the point of the game.
I wrote the game – and I’ve gotten better at it after playing a few thousand levels, but I still need to use hint mode for over 1/3rd of the levels.
The Crazy Portal
Obviously – I’m a numbers geek. But you don’t need numbers to see what a difference a portal (or two) makes.
And though one portal might not seem like a big deal, the transformation becomes obvious as soon as you reach two portals.
Since Flow Free came out, there are countless games with the same basic rules. You won’t find portals in any other game – well, except for the last pack in my other game, CTD: Shadows.
Try out portals for yourself and let us know what you think: Connect the Dots: Portals
Next Page: Levels