ISIS ushered in 2015 with the terrifyingly typical displays of brutality which initially put the group in the international community's crosshairs. They beheaded Japanese hostages, burned a Jordanian pilot alive in a cage and announced the death of American captive Kayla Mueller.
David Phillips, a former senior adviser to the State Department on Iraq, said ISIS was "on a roll" at the beginning of the year.
"They started off at a gallop," explained Phillips, now director of the program on peace-building and human rights at Columbia University.
But something was shifting as the year progressed.
If 2014 was all taking and consolidating territory — Mosul, Tikrit and more — the seizures of Palmyra and Ramadi this year were overshadowed by losses on the ground. Key leaders were killed and territory slipped away.
"In 2015, they've consistently had to abandon territory," Phillips said.
ISIS has been prevented from expanding operations in Iraq and Syria because of resistance they've encountered on the battlefield from Kurdish fighters backed by Western airstrikes, and Iran-backed militias, according to Phillips.
"The caliphate has been restricted, hemmed in and is under more pressure now than it ever has been particularly with the start of the Russian airstrikes," echoed Matthew Henman, head of IHS Jane's Terrorism and Insurgency Center.
But he and other analysts warned not to count ISIS out just yet: It's important to note that the caliphate has survived another full year.
"They remain hanging on," Henman said. "They're still in the game."
ISIS is still controlling "priority areas" in Syria and Iraq, Henman noted. The key cities of Fallujah, Ramadi, Mosul, Raqqa and Palmyra are still in ISIS hands despite billions of dollars worth of airstrikes against ISIS.
"The group doesn't need territory," Henman added. "If it loses control of those cities it reverts back to insurgent operations — the threat doesn't go away."
That's also because ISIS in 2015 has experienced a great deal of international expansion, with operations in Libya, Yemen, Saudi Arabia, Pakistan, Egypt and Afghanistan. Even if ISIS is wiped out in Iraq and Syria, Henman warned it's still got its hooks into other places.
"That ideology now is something which can't just be bombed away," he said.
ISIS appears to be driving that point home by increasing its attacks internationally and outside of their strongholds in Iraq and Syria, showing that it can strike out and hit its adversaries on their home turf.
"They've shown a consistent ability to project their terrorist goals," Phillips said. "It's a stark reminder that you're not safe anywhere."
Those attacks outside Iraq and Syria serve several purposes, analysts said.
First, it's direct retribution for Western airstrikes. It also serves as a distraction from whatever losses ISIS may be suffering, according to Henman.
"It's that show of strength to inspire fear into the heart of their enemies but also to buoy up their supporters at a time when they're coming under pressure," Henman said. "It's all about distracting away from their losses and reinforcing that narrative of continued expansion and momentum and winning victories."
It's also partially about pulling the West further into the fight, Henman and other experts said.
Analysts note that the first thing France did in response to the Paris attacks was to intensify airstrikes — which might play right into the ISIS-driven narrative.
"They're targeting farther abroad because they're trying to draw the West into a major conflict and use that as a basis for a third world war," Phillips said. "Their ideology is about the end of days and civilization as we know it being destroyed."
Whatever the goal — baited or otherwise — external actors have gotten more directly involved in the battle against ISIS this year.
The killing of the Jordanian pilot drew Amman into the fight against ISIS. Moscow intensified airstrikes against ISIS following the downing of the Russian passenger plane. The U.S. said it was sending special operations forces into Syria and the Paris attacks provoked further action, confirming longstanding fears about the potential of returned foreign fighters to carry out mass-casualty attacks in the West.
"It underlined that that threat is very real … It has catalyzed nations into acting," Henman said.
It also looks like the end of the year could hit ISIS particularly hard: an offensive against ISIS to retake Ramadi got under way on Tuesday and Iraqi forces have continued to advance in the days since.
Still, ISIS released a new audio message purportedly from its leader on Saturday mocking the U.S. for not putting boots on the ground. Abu Bakr al-Baghdadi said in the clip that airstrikes against ISIS were failing and the group was thriving.
It's become increasingly difficult to ascertain how ISIS really is faring in terms of financing and fighter strength, analysts said. The group is particularly good at managing its image and keeping their propaganda tightly controlled.
But while the various coalitions against ISIS have been criticized for a lack of cohesion or strategy, analysts note their impact can't be discounted.
"There's a lot going on in terms of the lack of unity by the international community but nevertheless ISIS has been hit quite severely," said Dr. Nelly Lahoud, a senior fellow for political Islamism at the London-based International Institute for Strategic Studies.
She said some of that is clear from ISIS' own propaganda releases. For example, ISIS has released several videos denouncing the recently-announced Saudi Arabian coalition against terrorism.
"If you read what ISIS is saying they are very annoyed. They are alarmed," Lahoud said. "It's more preoccupied with attacking others on the rhetorical level and on the ideological level more so than showing the territorial victories because they don't have any."
That level of alarm could bode worse for the West and the territories under ISIS control, she warned.
"One has to be scared and concerned about what the group might decide to do when it is losing," Lahoud said. "Mercy is not something that ISIS has shown to be part of its vocabulary … It is perhaps even more dangerous when it is losing."