David Clarke, 53, of Ryde Avenue in Nuneaton, pleaded guilty to seven charges over the stand-off at MFA Bowl in Nuneaton in October.
These included two counts of false imprisonment and possessing a samurai sword and knife.
At Warwick Crown Court, Clarke also admitted possessing a firearm with intent to cause fear of violence, possessing an imitation firearm with intent to cause an indictable offence and one count of criminal damage.
He denied a second count of possessing an imitation firearm with intent to cause an indictable offence.
According to a psychiatric report, he was suffering from depression at the time of the siege and had taken Tramadol, diazepam and vodka.
Sentencing was adjourned for a pre-sentencing report. Clarke will be back in court on 2 March.
Ch Supt Alex Franklin-Smith, from Warwickshire Police, said Clarke would “have realised the impact his selfish actions would have on the victims and the many people and families who were out enjoying the start of the school half-term holiday”.
He said he would like to thank “the many people who were caught up” in the event for their “calmness, co-operation and support” and the incident “brought out the best” in Nuneaton people.
Ch Supt Franklin-Smith said: “Local businesses providing refuge for people caught up in the events and local taxi and bus companies providing people with free lifts home were just some of the examples.”